Tetrads are also known as which of the following?

Tetrads are commonly referred to as bivalents during the process of meiosis, particularly in prophase I. A tetrad consists of a pair of homologous chromosomes, which each have been duplicated. Thus, during this stage, the homologous pairs align closely together, resulting in a structure made up of four chromatids—two from each homologous chromosome. The term "bivalent" captures this arrangement of two homologous chromosomes, hence, it is synonymous with tetrads.

Understanding why the other options do not fit is important. Sister chromatids refer specifically to the two identical copies of a chromosome that are joined together by a centromere, which is distinct from the arrangement seen in tetrads. Homologous pairs denote the two chromosomes, one from each parent, that are similar in shape, size, and genetic content, but do not specifically highlight their interaction during meiosis. Chromosomal pairs is a more general term that does not specifically denote the structure or process associated with tetrads or bivalents. The term bivalent emphasizes the connection and pairing of homologous chromosomes during meiosis, which is a key aspect in understanding genetic variation and genetic recombination that occur during this stage.