Approximately 99% of the Microbes in the Intestines Are Obligate

Multiple Choice

Approximately 99% of the microbes in the intestines are obligate anaerobes. We have plenty of blood vessels that can bring oxygen to the tissues of the intestines. Why would there be obligate anaerobes within these areas?

A) The bacteria in the intestines are protected from exposure to the oxygen in the tissues by the lining of the intestines.
B) The bacteria consume all the oxygen in the tissue areas brought by the blood vessels, creating an anaerobic environment.
C) The inside space of the intestines is highly anaerobic. It is deep inside the body where oxygen cannot reach and it is not supplied with blood.
D) The aerobic microbes are outcompeted for nutrients in these areas by the anaerobic microbes.
E) The inside space of the intestines is highly anaerobic. It is deep inside the body where carbon dioxide accumulates.