Triangle X Y Z is similar to triangle R S T such that X , Y

Choice C is correct. It’s given that triangle $XYZ$ is similar to triangle $RST$, such that $X$, $Y$, and $Z$ correspond to $R$, $S$, and $T$, respectively. Since corresponding angles of similar triangles are congruent, it follows that the measure of $Z$ is congruent to the measure of $T$. It’s given that the measure of $Z$ is $20/mo>$. Therefore, the measure of $T$ is $20/mo>$.

Choice A is incorrect and may result from a conceptual error.

Choice B is incorrect. This is half the measure of $Z$.

Choice D is incorrect. This is twice the measure of $Z$.