Question

which concept is used to prove that the opposite sides of a parallelogram are congruent? congruent rectangles similar rectangles congruent triangles similar triangles

Explanation:

To prove opposite sides of a parallelogram are congruent, we can divide the parallelogram into two congruent triangles by drawing a diagonal. Then, using properties of congruent triangles (such as Side - Angle - Side (SAS) congruence criterion), we can show the sides are equal. Rectangles are not relevant here and similar triangles don't prove congruence of sides directly for this purpose.

Answer:

C. congruent triangles