Desulfovibrio is a bacterium that breaks down organic matter which it must have and uses sulphate not oxygen as an electron acceptor. As a result, it produces hydrogen sulphide (\[{{H}_{2}}S\]), accounting for the 'rotten egg' smell of swamp muck. Oxygen is a deadly poison to Desulfovibrio. We would call Desulfovibrio a(n):

• A. facultatively anaerobic chemoautotroph.
• B. obligately anaerobic chemoheterotroph.
• C. facultatively aerobic chemoheterotroph.
• D. obligately anaerobic chemoautotroph.