Here's why:

* Synapsis: This is the process where homologous chromosomes pair up during prophase I of meiosis.

* Homologous Chromosomes: These are pairs of chromosomes that carry the same genes, one from each parent.

* Tetrad: Once the homologous chromosomes are paired, they are held together by proteins and form a structure called a tetrad. A tetrad consists of four chromatids, two from each homologous chromosome.

Let me know if you'd like more details on meiosis!