Photons Have No Mass, and Einstein's Theory of General Relativity

Photons have no mass, and Einstein's theory of general relativity says

A) their paths through spacetime are curved in the presence of a massive body.
B) their apparent speeds depend on the observer's frame of reference.
C) they should not be attracted to a massive object.
D) their wavelengths must remain the same as they travel through spacetime.
E) their wavelengths would grow longer as they travel through empty space.