A Car Going Around a Curve of Radius R at a Speed

Multiple Choice

A car going around a curve of radius R at a speed V experiences a centripetal acceleration a_c.What is its acceleration if it goes around a curve of radius 3R at a speed of 2V?

A) (2/3) a_c
B) (4/3) a_c
C) (2/9) a_c
D) (9/2) a_c
E) (3/2) a_c