Final answer:
A standard square consists of four right angles, each measuring 90 degrees.
Step-by-step explanation:
The question asks about the measure of an angle in a standard square. A square has four equal sides, and at each corner, the sides meet to form a right angle. A right angle is an angle of 90 degrees. Therefore, the correct answer to the question is C. 90 degrees, as each angle in a square is a right angle.