The Port Isabel lighthouse blinked a patient rhythm as I followed the narrow boardwalk over the marsh. The planks thudded under my sneakers, each step keeping time with the distant clang of a buoy. Old Man Rivas had sworn he saw someone slip behind the bait shop after closing, and the note tucked under its door - meet at low tide - still crinkled in my pocket. At the end of the boardwalk, the mud took my weight with a sigh. A line of shoe prints stitched the silt, veering toward the pilings where shrimp boats swayed. I crouched and touched a print; the edges were sharp, fresh. A gull's cry scraped the dark. Something flashed in the weeds, and I fished out a rusted anchor charm on a broken chain. It matched the bracelet Celia wore yesterday. The tide, dark and patient, was climbing the poles, swallowing the lower rungs of the ladder. I glanced back at the tiny glow of town, then forward into the salt-bitter wind. If I was going to learn who left that note, I had to move now-before the water erased everything.

Which plot element is primarily being developed in this excerpt?

On the courthouse steps in San Antonio, I unfolded the county map until it trembled in the breeze. In an hour, I'd stand before the council to argue against selling our family pasture to the pipeline. The mesquite's shadow freckled the page, and the smell of dust lifted a door in my head. I was small again, walking beside Abuela across the Panhandle in a summer that never ended. Heat shimmered in the distance; grasshoppers clicked like tiny clocks. She carried a blue enamel pot in the crook of her arm and a tin cup swung from her belt. "Water first," she said, tapping the cup, "then the rest." When we reached the windmill, she let the cup dip once, twice, and pressed it into my hands as if it were a treaty. The flashback broke when a bus hissed to the curb. The map was still shaking. I traced the blue line of our creek with my finger and felt the tin cup's cool weight again. It wasn't just land I was protecting; it was a promise Abuela had poured into me, one careful sip at a time.

How does the flashback contribute to the story's overall development?

The storm had been building all afternoon, but we thought the arroyo was dry enough for a quick shortcut. The first drops spattered the dust like coins. We had almost cleared the narrow bend when the roar arrived - low at first, then a freight train. Mateo froze. I looked upstream and saw the wall of muddy water rounding the slick rock, carrying branches, a cooler, somebody's stray boot. "Climb!" I shouted, shoving him toward a ledge no wider than a book. His sneaker slipped; his fingers found nothing. The flood smacked my shins, cold and violent. In that breath, everything shrank to his wrist and my grip. I lunged, catching him by the jacket sleeve as the current yanked his legs away. The seam tore with a sound I'll hear forever. My other hand scraped for the jut of rock; knuckles split. "Hold!" I growled through my teeth, hauling sideways, feeling the fabric stretch, stretch - and then Mateo's palm slammed into mine. Together we scrambled up the ledge as the brown surge exploded past below, raging at the empty space where we had been.

Which plot element is most clearly depicted in this excerpt?

The gym smelled like varnish and oranges from halftime, and our science fair tables were lined up like islands under the rafters. I set my terrarium near the center, checked the mister, and noticed the lid had shifted a fraction. A line of sugar ants stitched from the wall to the snack counter, threading through a gap beneath the bleachers. Above us, the new light fixtures hummed, a restless sound that made the banners tremble. "Weird," Tasha said, wrinkling her nose, "it's usually silent before awards." Coach wheeled in a box fan, its cord stretched taut across the floor like a tightrope. I taped mine down and glanced again at the rafters. A dark patch blossomed near the vent, then shrank, as if the ceiling were breathing. The custodian swatted at the humming with a folded brochure and frowned at the exit doors. I tightened the terrarium lid and slid it closer to the judges' aisle. Everything looked normal, I told myself. But as the hum surged and the ants quickened, I felt the moment leaning forward, waiting for something to give.

Which structural device is used in the excerpt, and what is its purpose in the story's development?