What is the standard equation of a circle?

(x + h)2 + (y + k)2 = r

(x – h)2 + (y – k)2 = r

(x – h)2 + (y – k)2 = r2

(x + h)2 + (y + k)2 = r2

The graph below shows the height of a projectile t seconds after it is launched. if acceleration due to gravity is -16 ft/s2, which equation models the height of the projectile correctly?