The correct option is C 2mgRπ
We know that, the potential energy is calculated by:
PE=mgh
'h' here represents the distance of the center of mass from the zero potential energy line.
In case of a half ring, its center of mass lies at a distance of 2R/π from its center.
So, in this case, we get h=2R/π
∴PE=mg2Rπ=2mgRπ