Two Cars Start at the Same Point,but Travel in Opposite $\frac { \pi } { 2 } \mathrm { R }$

Multiple Choice

Two cars start at the same point,but travel in opposite directions on a circular path of radius R,each at speed v.While each car travels a distance less than $\frac { \pi } { 2 } \mathrm { R }$ ,one quarter circle,the center of mass of the two cars

A) remains at the initial point.
B) travels along a diameter of the circle at speed v' < v.
C) travels along a diameter of the circle at speed v' = v.
D) travels along a diameter of the circle at speed v' > v.
E) remains at the center of the circle.