选择题
2013 AMC 8 Problem 25: Rolling Ball Track
A ball with diameter 4 inches starts at point A to roll along the track shown. The track is comprised of 3 semicircular arcs whose radii are R1=100 inches, R2=60 inches, and R3=80 inches, respectively. The ball always remains in contact with the track and does not slip. What is the distance the center of the ball travels over the course from A to B?
A.
238π
B.
240π
C.
260π
D.
280π
E.
500π