Answer:
B. S phase.
Step-by-step explanation:
The interphase and M (mitosis) phase are the two phases of a cell cycle. Interphase is further divided into G1, S and G2 phases. About 90 % time of the cell cycle is occupied by interphase and rest 10% taken by M-phase. Interphase begins with G1 phase the cell synthesises proteins and increase in size. Directly after G1 phase, S phase or synthesis phase occurs. During S-phase replication of DNA occurs. Thus, the cell makes an identical copy of each of its chromosomes.