Answer:
A. G1, C. G2
Step-by-step explanation:
Cell cycle consists of G1, S, G2 and M phases. During G1 stage, all cell contents except DNA are replicated. During S stage, DNA is replicated. During G2 stage, cell checks for any error in replicated DNA and prepares for M stage. During M stage, Mitosis occurs in cell which ends by production of two cells from one.
There are two types of DNA check points. One is present at G1/S boundary. Here it is made sure that DNA is damage free because in next stage it has to be replicated. So in absence of checkpoint the newly synthesized DNA strand would also accumulate the damage. Another check point is present at G2/M boundary. This is like a final check before the cell enters mitosis and is divided. If some damage was not detected at G1/S boundary or an error occurred during replication process, it is rectified at this checkpoint.