Step 1: Recall phases of the eukaryotic cell cycle.
Between G1 and G2 lies the S phase (synthesis phase), where DNA replication occurs. This results in doubling of the DNA content, even though chromosome number remains the same.
Step 2: Check each option.
(A) Incorrect — mitosis involves separation of already replicated DNA.
(B) Incorrect — DNA replication occurs before meiosis I, not between prophase I and II.
(C) Correct — DNA replication takes place in S phase located between G1 and G2.
(D) Incorrect — M phase involves division, not DNA doubling.
Step 3: Conclusion.
Thus, DNA doubling occurs between G1 and G2.