沼气发酵中产甲烷细菌是

A、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 14px">专性厌氧菌</span>

B、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 14px">兼性厌氧菌</span>

C、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 14px">好氧菌</span>

D、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 14px">微好氧菌</span>