Can someone explain this question...

If chromosomal duplication before tetrad formation occurred twice during spermatogenesis, while the other steps of meiosis proceeded normally, which of the following would result from a single spermatocyte?

A. One tetraploid sperm
B. Four diploid sperm
C. Four haploid sperm
D. Eight haploid sperm

The correct answer choice is B, 4 diploid sperm.

Synthesis occurs as the cell goes from a spermatogonium to primary spermatocyte. If you have two rounds of synthesis, then all of the chromosomes in the primary spermatocyte would 4 sister chromatids. After tetrad (or rather octet in this case) formation and meiosis I, each of the secondary spermatocytes will have 23 chromosomes, all of which still have 4 sister chromatids. Finally, after meiosis 2, each of the sperm cells will have 23 chromosomes, each of which has two sister chromatids. This is of course assuming that two sister chromatids go to each daughter cell during meiosis 2. Otherwise you would have a situation where some chromosomes were N, some 2N, some 3N.

I hope this helps...