The gravitational potential energy of a body of mass $m$ raised to a height $h$ above the ground (where $g$ is acceleration due to gravity) is:

Near Earth's surface (where $g$ is approximately constant), gravitational potential energy stored when an object of mass $m$ is lifted by height $h$ equals the work done against gravity: $W = F \cdot s = (mg)(h) = mgh$. The reference (zero) for PE is conventional, usually the ground. Lower than ground gives negative PE. Option A ($\tfrac{1}{2} mgh$) is a common trap — students confuse the $\tfrac{1}{2}$ factor that comes from spring or kinetic energy with gravitational PE.