Which one of the following statements about the cell cycle is correct?
a. dna is replicated during m-phase.
b. cell growth occurs during g1 and g2, but not s-phase.
c. most cells in the human body are in g0. both g2 and m-phase are 4n in e. coli.
d. g1 is easily distinguished from g2 in the microscope.

The correct answer is option C. "Most cells in the human body are in G0".

Explanation:

G0 is the phase of the cell cycle at which the cells are in a quiescent state. Basically, this is considered as a "normal" state for the cells, because at this point the cells are neither dividing nor preparing to divide. Most cells in the human body are in G0, because most cells in the body are fully differentiated, particularly adult neuronal cells.