Final answer:
Secondary oocytes (option c) and cells beginning meiosis II are diploid. Sperm are haploid, as they are the end product of spermatogenesis after the completion of both meiosis I and II.
Step-by-step explanation:
The question regarding meiosis asks which cells are diploid. During the process of spermatogenesis, primary spermatocytes, which are diploid, go through the first cell division of meiosis I to produce haploid secondary spermatocytes. These secondary spermatocytes then undergo meiosis II to become spermatids, which are also haploid cells. In oogenesis, the primary oocyte, which is diploid, divides into a secondary oocyte and a polar body. The secondary oocyte remains diploid until it is fertilized. If fertilization occurs, the secondary oocyte completes meiosis II and becomes a haploid ovum. Therefore, the secondary oocytes and cells beginning meiosis II are diploid, while sperm, being the end product of spermatogenesis, are haploid.