A Runner Circles a Track of Radius 100 M in 100

Multiple Choice

A runner circles a track of radius 100 m in 100 s moving at a constant rate.If the runner was initially moving north,what has been the runner's average acceleration when halfway around the track?

A) At a constant rate,the average acceleration would be zero.
B) 2 m/s²,west
C) 0.25 m/s²,south
D) No answer is correct.