Australian AMC 2013 - Intermediate Question 19

Question 19

A circular wheel of radius r rolls, without slipping, through half a revolution. The point X is on the horizontal diameter at the start.

Question illustration

The distance between the starting and finishing position of the point X is

$2\pi r$
$(\pi+2)r$
$(\pi-2)r$
$2(\pi+1)r$
$2(\pi-1)r$