SAT Question d21270da: Lines, Angles, and Triangles answer and explanation with Desmos solution

Choice B is correct. In the figure shown, transversal $t$ intersects lines $r$ and $s$. Two lines intersected by a transversal are parallel if and only if a pair of alternate interior angles have equal measure. The angle marked $24^{\circ }$ and the angle marked $x^{\circ }$ form a pair of alternate interior angles. Therefore, $x=24$ is sufficient to prove that lines $r$ and $s$ are parallel.