Final answer:
A parallelogram can be considered a rectangle if it has four right angles and opposite sides are parallel and equal in length.
Step-by-step explanation:
A parallelogram can be considered a rectangle if it has four right angles (90 degrees each). In other words, all four angles of the parallelogram must be equal to 90 degrees. This means that opposite sides of the parallelogram are parallel and equal in length, and all four sides are also equal in length.
For example, if we have a parallelogram with angles measuring 90 degrees, such as ABCD, where AB is parallel to CD and AD is parallel to BC, then this parallelogram is a rectangle.