Question

Which transformation will always map a parallelogram onto itself?

Answer 1

Answer:  C) a 180 degree rotation about its center

Explanation:

Draw out a rectangle and make sure it's not a square. So you could have it be longer than it is tall. Imagine rotating that rectangle 180 degrees. The before and after (preimage and image) will be identical. The same applies if we slanted the sides of this rectangle. This shows that any parallelogram has rotational symmetry.

Side note: any rectangle is a parallelogram, but not the other way around.

Answer 2

Answer:

с.a 180° rotation about its center