Theorems about Triangles Practice Test

In the diagram, $\triangle RST$ is shown. Point $U$ lies on $RS$ with markings indicating $RU \cong US$, and point $V$ lies on $ST$ with markings indicating $SV \cong VT$. Segment $UV$ is drawn. No angle markings, no right-angle boxes, no parallel arrows, and no lengths are given; the diagram is not drawn to scale. Which statement must be true?

In the diagram, $\triangle ABC$ is shown. Point $D$ is marked as the midpoint of $\overline{BC}$ (with $BD\cong DC$). Point $E$ is marked as the midpoint of $\overline{AC}$ (with $AE\cong EC$). Segment $\overline{DE}$ is drawn. No other markings are given, and the diagram is not drawn to scale.

Which statement must be true?