The proton-proton chain (a) combines two hydrogen nuclei to produce a single helium nucleus and energy.(b) splits a helium nucleus to produce 4 hydrogen nuclei and energy.(c) is the mechanism that increases the temperature between the photosphere and corona of the sun.(d) is the interactions between protons in earth's atmosphere that produces auroras.(e) produces energy in the core of the sun in the form of gamma-rays, positrons, and neutrinos.