The function h(t) = −16t2 + 48t + 36 models the height of a ball, in feet, at t seconds after being thrown into the air.
 Part A
 What feature of the function represents the highest point of the ball?
 A. end behavior
 B. symmetry
 C. vertex
 D. zero
 Part B
 What is the highest point of the ball, in feet?