已知3克乙烷在常温下完全燃烧放出的热量是155.98kJ，则下列乙烷燃烧热的热化学方程式书写正确的是（  ）

A．2C2H6(g)+7O2(g)=4CO2(g)+6H2O(g)△H ="-2119.6" kJ/mol

B．C2H6(g)+5/2O2(g)=2CO2(g)+3H2O(g)△H ="-1559.8kJ/mol"

C．C2H6(g)+7/2O2(g)=2CO2(g)+3H2O(g)△H ="-1559.8" kJ/mol

D．C2H6(g)+7/2O2(g)=2CO2(g)+3H2O(l)△H ="-1559.8" kJ/mol