- A G1 phase, before DNA synthesis begins
- B S phase (Synthesis)
- C G2 phase, after DNA synthesis ends
- D Mitosis, during chromosome separation
Correct answer: B. S phase (Synthesis)
Explanation: DNA replication occurs during S phase (Synthesis phase) of interphase, before cell division begins.
Concept context
Mitosis and meiosis: how cells divide for growth, repair, and reproduction.