Seminiferous tubule diagram and labelling

The correct answer should be A according to the answer key, I thought it would be B or C?

The seminiferous tubules of the mammalian testis are the site of ongoing spermatogenesis in the adult. It can’t be mitosis as this region is where the cells become haploid. You can see in X that PAIRS of chromosomes are separating and not individual chromatids so it can’t be meiosis II. It can’t be mitosis as this region is where the cells become haploid. Hope this helps!