Nice problem!
Look. At point A the road changes from a straight line to a circular line, then the motion changes from rectilinear to circular motion. So at that point, there is a sudden change in the acceleration, which for sure the passengers feel.
At point B, the circular motion changes from anticlockwise to clockwise, then there is another sudden change in the acceleration.
At point C, the road changes from circular to straihgt line, then the motion changes from rectilinear to circular, which produces a new sudeen change in acceleration.
Then the answeer is the last option, at points A, B and C.