sat-dog

Choice B is correct. It’s given that triangle $ABC$ is congruent to triangle $DEF$. Corresponding angles of congruent triangles are congruent and, therefore, have equal measure. It’s given that angle $A$ corresponds to angle $D$, and that the measure of angle $A$ is $18°$. It's also given that the measures of angles $B$ and $E$ are $90°$. Since these angles have equal measure, they are corresponding angles. It follows that angle $C$ corresponds to angle $F$. Let $x°$ represent the measure of angle $C$. Since the sum of the measures of the interior angles of a triangle is $180°$, it follows that $18°+90°+x°=180°$, or $108°+x°=180°$. Subtracting $108°$ from both sides of this equation yields $x°=72°$. Therefore, the measure of angle $C$ is $72°$. Since angle $C$ corresponds to angle $F$, it follows that the measure of angle $F$ is also $72°$.

Choice A is incorrect. This is the measure of angle $D$, not the measure of angle $F$.

Choice C is incorrect. This is the measure of angle $E$, not the measure of angle $F$.

Choice D is incorrect. This is the sum of the measures of angles $E$ and $F$, not the measure of angle $F$.