Which of these is a simple sentence?

a.
The clown frightened the little girl, and she ran off screaming when she saw it.
c.
My brother is fun to be around until he starts making animal sounds.
b.
My aunt enjoyed taking the hayride through the overgrown pumpkin patch.
d.
Even though many kids may not like fall festivals, I love going to them.

Please select the best answer from the choices provided

A
B
C
D