A horizontal gas cylinder contains a gas at high pressure. A cross-section of the cylinder's hemispherical end-cap is shown below, with a point X X\,X marked on the curved inner surface. The tangent to the curved surface at X X\,X makes an angle of 30∘ 30^\circ\,30∘ with the horizontal longitudinal axis of the cylinder.
Which arrow represents the correct direction of the force exerted by the gas pressure on the inner wall of the cylinder at point XXX?
FCF_CFC
FDF_DFD
FAF_AFA
FBF_BFB