State which of the decays or reactions that follow violate one or more of the conservation laws, and give the law or laws violated in each case:

(a) p ⁺ → n + e ⁺ + v_e,

(b) n → p ⁺ + π^– ,

(c) e ⁺ + ^{e –} → γ,

(d) p ⁺ p ^– → γ + γ, and

(e) v_e + p → n + e ⁺ .