化学反应N2+3H2=2NH3的能量变化图所示,该反应的热化学方程式是( )A.N2(g)+3H2(g)?2NH3(l)△H=2(a-b+c) kJ/molB.N2(g)+3H2(g)?2NH3(l)△H=2(a-b-c) kJ/molC.12N2(g)+32H2(g)?NH3(l)△H=(b+c-a) kJ/molD.12N2(g)+32H2(g)?NH3(g)△H=(a+b) kJ/mol