Is there any point along the path of a projectile where its velocity and acceleration vectors are;

Question

a) perpendicular to each other
b) parallel to each other?

My ans:
a) I thought its perpendicular at the peak but I didn't know how to explain it
b) I thought they would be parallel when the ball is either going up or down

Answer 1

a) is correct. Gravity is downward, velocity it parallel to Earth.
b) correct.