Meiosis reduces chromosome number in gamete formation

Steps:

• Cell X is diploid with 2n=8 chromosomes before meiosis.
• In meiosis I, homologous chromosomes separate, producing cell Y with n=4 chromosomes (each duplicated).
• In meiosis II, sister chromatids separate, producing cell Z with n=4 chromosomes (now single).
• Fly cell division follows standard eukaryotic meiosis, halving chromosomes twice.

Why C is correct:

• Meiosis produces haploid cells with half the diploid number, so both post-meiotic cells have 4 chromosomes per the law of chromosome segregation.

Why the others are wrong:

• A: Cell Z retains 8, ignoring meiosis II reduction.
• B: Cell Y retains 8, ignoring meiosis I halving.
• D: Both retain 8, describing mitosis, not the diagram's meiotic stages.

Final answer: C