Refine Designs Using Chemical Evidence Practice Test

A class tested two materials for disposable gloves to handle a dilute bleach solution (sodium hypochlorite). Material A (thin vinyl) showed no visible damage after 20 minutes but tore easily during use. Material B (nitrile) did not tear but became slightly stiff and showed faint discoloration after 20 minutes. The task requires 15-minute handling with good dexterity and low failure risk. Which refinement best balances the evidence from both tests?

A student designed a copper wire sensor to be used in a saltwater (NaCl) aquarium to measure conductivity. Copper was chosen because it conducts electricity well. After 1 month, the copper wire turned green in spots, the measured conductivity drifted over time, and fish health concerns were raised. Which refinement best addresses the chemical issue indicated by the evidence?