Which of these processes likely contributes LEAST to growth of microbes in subsurface environments

Question

Quizplus · Accepted Answer

Organic detritus deposition from surface layers is less likely to contribute to the growth of microbes in subsurface environments as organic matter is typically scarce in such environments. The other options involve processes that can provide energy or carbon sources for subsurface microbial growth, such as chemolithoautotrophy (using inorganic compounds as energy sources and CO2 as a carbon source), chemolithoheterotrophy (using inorganic compounds as energy sources and organic compounds as carbon sources), and chemoorganoheterotrophy (using organic compounds both as energy and carbon sources).

Which of These Processes Likely Contributes LEAST to Growth of Microbes