Answer:
I guess it's d because age environment heredity Nd maturation r more obvious factors if we compre with only physical fitness
T = 4 sec / 2 = 2 sec period of revolution
S = 2 pi R = 2 * pi * 1.75 m = 11 m
V = S / T = 11 m / 2 sec = 5.5 m/s speed of object
c they obey inverse square law