What do you mean by "answer"? General relativity showed that gravity is really the result of masses curving space-time. Particles with mass are confined to follow the curvature of space-time. If there is a large mass near by, freely falling particles will follow the curvature to the mass. What we call gravity is the result of the surface of a mass, like the earth stopping us from freely falling to the center. The surface obstructs our fall and we experience a 'pull" downward. In principle, anything acting in space-time has to be contained in space-time. So photons, the carriers of electromagnetic force, travel on the shortest paths through space-time while following the curvature. One of the biggest issues though is the inability to derive a quantum theory of gravity starting with general relativity. So while the electromagnetic, weak and strong forces all have to operate in space-time, we have yet to develop a self consistent, finite model that yields testable results incorporating all the fundamental forces.