Initial acceleration of a stone stuck in a car tire groove

[musicfairy]

A car travels forward with constant velocity. It goes over a small stone, which gets stuck in the groove of a tire. The initial acceleration of the stone, as it leaves the surface of the road, is
(A) vertically upward
(B) horizontally forward
(C) horizontally backward
(D) zero
(E) upward and forward, at approximately 45° to the horizontal




I think it's A because as it leaves the surface of the road it is on the bottom of the circle, and centripetal force points vertically up. Is this correct?

 

[Rake-MC]

That looks fine to me, however; if the car was accelerating forwards and not traveling at a constant velocity, you can see that there would be vehicular acceleration as well as centripetal acceleration such that the answer would look a lot more like E.