#### Answer

(a) Square: 4 right angles, all sides have equal lengths.
(b) Rectangle: 4 right angles, opposite sides have equal lengths.
(c) Parallelogram: 0 mandatory right angles, opposite sides have equal lengths.

#### Work Step by Step

Refer to the image shown below.
(a) The first image is a square. There are 4 right angles, at each corner. All the sides are the same length.
(b) The second image is a rectangle. There are 4 right angles, at each corner. Opposite sides have the same length.
(c) The third image is a parallelogram. There are no right corners (a parallelogram can have right corners, as in the case of a rectangle or square, but does not have to). Opposite sides have the same length (and are also parallel).