Explanation
Correct answer: C.
Choice C is correct. It's given that triangle is similar to triangle . Corresponding angles in similar triangles have equal measure. Angle and angle represent the same angle. It follows that angle and angle have equal measure and are corresponding angles. It's given in the figure that angle and angle are right angles and therefore have equal measure. It follows that angle and angle are corresponding angles. Therefore, angle and angle are corresponding angles and have equal measure. It's given that the measure of angle is , so the measure of angle is .
Why the other choices are wrong
Choice A
Choice A is incorrect and may result from conceptual errors.
Choice B
Choice B is incorrect and may result from conceptual errors.
Choice D
Choice D is incorrect and may result from conceptual errors.