Which of the following statements are correct?
A. If one interior angle of a parallelogram is a right angle, then the parallelogram must be a rectangle.
B. If two diagonals of a rectangle are perpendicular, then the rectangle must be a square.
C. If two diagonals of a rhombus are equal, then the rhombus must be a square.
D. If one interior angle of a rhombus is a right angle, then the rhombus must be a square.
E. If two diagonals of a parallelogram are equal, then the parallelogram must be a rectangle. Enter all correct options as a list of letters, separated by commas.
A: If one angle in a parallelogram is 90 degrees, that means the rest have to be 90 degrees. Therefore, this is TRUE.
B: A rectangle already has perpendicular sides, and a rectangle can't be a square. Therefore, this is FALSE.
C. A rhombus is a square. This is TRUE.
D. A rhombus is a square. This is TRUE.
E. The sides of a parallelogram are different, as well as a rectangle. This is FALSE.
The answer is A, C, and D.