The Dutch microbiologist van Niel first demonstrated anoxygenic photosynthesis in soil and water bacteria. He generalized his work by hypothesizing that

A) every molecule in nature can be used as a source of nitrogen by some microorganism.
B) photosynthesis results in oxygen production.
C) microbes are found in every environment on Earth.
D) microbes cannot live deep within Earth.
E) photosynthesis occurs deep within Earth.