Answer:
DNA replication occurs during the S phase of interphase. The S phase is the second phase of the interphase, which follows the G 1 phase.
Explanation: Interphase is the portion of the cell cycle that is not accompanied by observable changes under the microscope, and includes the G1, S and G2 phases. During interphase, the cell grows (G1), replicates its DNA (S) and prepares for mitosis (G2). A cell in interphase should not be confused with a cell in quiescent state, which represents most of the cell’s lifetime.