In which of the following cellular processes do homologous chromosomes pair up to form tetrads?

Chromosomes pair up during meiosis, more specifically during metaphase I of meiosis I. In meiosis, pairs of chromosomes are separated to form cells that are haploid or contain half the amount of DNA as the original cell. In mitosis, individual chromosomes line up and are separated into their respective sister chromatids. This same process of separating individual chromosomes also occurs in meiosis, but in meiosis II, not meiosis I. During interphase, the cell prepares for cell division by duplicating organelles and replicating DNA. No pairing of chromosomes occurs during Interphase.[Life Science]