This will be the solution for a two-order inequality.

a.) a point
b.) a line
c.) a half-plane
d.) the intersection of two half-planes

The best and most correct answer among the choices provided by your question is the third option or letter C. The solution of a two-order inequality is a half-plane. 

A half-plane is a planar region consisting of all points on one side of an infinite straight line, and no points on the other side. If the points on the line are included, then it is called an closed half-plane. If the points on the line are not included, then it is called an open half-plane.

I hope my answer has come to your help. Thank you for posting your question here in .