The correct option is B G1− phase
A cell enters the mitotic phase after the G1 and the S phase. Mitotic phase is when the cell completes prophase, metaphase, anaphase and telophase. And after mitotic phase, the cell enters the G1 phase. So it is the G1 phase that separates the post-mitotic and the premitotic phase. G1 phase is particularly important in the cell cycle because it determines whether a cell commits to the division or to leave the cycle. Is a cell is signalled to remain undivided, instead of moving onto the SPhase, it will leave the G1 phase and move into a state of dormancy