Answer:
D. The amount of rotation of one side.
Explanation:
We need to explain the statement " What affects the size of an angle? ".
Given options are
A. The length of its sides
B. The direction of one side
C. Its orientation in space
D. The amount of rotation of one side.
The correct option would be :
D. The amount of rotation of one side.
Because as the one side rotated, it makes a greater or smaller arc between the two lines. That would affects the size of an angle.