The Aerated Upper Layer of Soil Is Likely to Have

Multiple Choice

The aerated upper layer of soil is likely to have ________ concentrations of H₂ for aerobic H₂-oxidizing Bacteria, so these bacteria likely ________.

A) high / thrive in such conditions by not competing with chemoorganotrophs
B) high / generate important reducing equivalents as byproducts for other microorganisms in the soil
C) low / do not occur in such habitats
D) low / will need a chemoorganotrophic way to grow as well