What could be the reason for the faster rate of decomposition in the tropics?

Humus is ....... in nature.

In decomposition,humus is further degraded by some microbes and the release of inorganic nutrients occurs by the process known as...

Given below are two statements:
Statement $I:$
Decomposition is a process in which the detritus is degraded into simpler substances by microbes.
Statement $II:$
Decomposition is faster if the detritus is rich in lignin and chitin.
In the light of the above statements,choose the correct answer from the options given below:

Decomposition is defined as .....

The main role of bacteria in the carbon cycle involves: