According to the topic, a geometric figure is a simple combination of a hemisphere in the upper part and a cylinder in the lower part.

Because the radius of a hemisphere is 1, its volume is 12×43×π×? 12=2π3

The radius of a cylinder is 1 and the height is 1, so its volume is π× 12× 1=π.

The volume of this geometry is 2π3+π=5π3.

So choose C.