The statement that best summarizes the rotations that turn a square onto itself is:
B. A square will rotate onto itself after 90-degree, 180-degree, 270-degree, and 360-degree rotations.
This is because a square has four symmetrical positions that it can occupy during rotations. It will align with its original position after rotating by 90 degrees, 180 degrees, 270 degrees, and a full 360 degrees.