A particle is constrained to move on a straight line path. It returns to the starting point after 10 sec . The total distance covered by the particle during this time is 30 m . Which of the following statements about the motion of the particle is false
A. Displacement of the particle is zero
B. Average speed of the particle is `3m//s`
C. Displacement of the particle is 30m
D. Both (a) and (b)