Here is the first sign that should tell you this isn't a rectangle.
d=_/w^2+l^2 is the equation to solve the diagonal of a rectangle
if you plug in 21 and 20, d would equal 29 not 28 so for that reason alone it is not a rectangle.
I am about 90% sure the correct answer is B. I hope this helps let me know if I was right.
Option B!
