Imagine giving each wheel a half turn about its centre. Which wheel would then look different from before?

In (a), (b), (c) and (d) every shaded part has a shaded partner directly opposite it, so a half turn leaves the wheel looking exactly the same. In (e) two parts on the right are shaded but on the left only one of the matching opposite parts is, so after a half turn the picture changes: (e) is the odd one out.