Final answer:
Metaphase I is distinguished from metaphase II by the alignment of homologous chromosomes on the spindle.
Step-by-step explanation:
Metaphase I is distinguished from metaphase II by the alignment of homologous chromosomes on the spindle. In metaphase I, the paired homologous chromosomes line up along the equator of the cell, while in metaphase II, it is sister chromatids that line up along the equator of the cell.
What distinguishes metaphase I from metaphase II is the alignment of homologous chromosomes. During metaphase I, spindle fibers attach to the paired homologous chromosomes, and these paired chromosomes line up along the equator of the cell. This specific alignment occurs only in metaphase I of meiosis. In contrast, metaphase II involves the alignment of sister chromatids along the cell equator, which is a process also seen in mitotic metaphase and metaphase of meiosis II. Therefore, the correct answer is a) Alignment of homologous chromosomes.