In the Sun much of the energy results from a set of reactions called ... ...

 In the Sun much of the energy results from a set of reactions called the pp chain. The first step involves two protons colliding to make heavy hydrogen. Which of the following expresses this reaction?
(A) 1H + 1H → 2H + γ
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in 16. Atomic and Nuclear Physics