Gravity as the limit of the type-II superstring theory

The amplitude for graviton-graviton scattering in D dimensions is calculated in the tree approximation. We show explicitly that in ten dimensions this agrees completely with the zero-slope limit of the four-particle tree amplitude given by the type-II superstring theory. When six of the spatial dimensions are compactified it is shown that the four-particle string amplitude agrees with the helicity amplitudes obtained from general relativity in four dimensions.