已知热化学方程式：

① C₂H₂(g) +5/2O₂(g) == 2CO₂(g)＋H₂O(l) ΔH1＝-1301．0 kJ·mol^-1

② C(s)+ O₂(g) == CO₂(g) △H2＝-393．5 kJ·mol^-1

③ H₂(g)+ 1/2O₂(g) == H₂O(1) △H3 = -285．8 kJ·mol^-1

则反应④ 2C(s)+ H₂(g) == C₂H₂(g)的△H4为[ ]

A．+228．2 kJ·mol^-1

B．-228．2 kJ·mol^-1

C．+1301．0 kJ·mol^-1

D．+621．7 kJ·mol^-1