In which cells of the body are chromosomes not arranged in pairs?

Germ cells are the correct answer because they are haploid, meaning they contain only one set of chromosomes, instead of the diploid arrangement seen in somatic cells and most other cell types. In humans, germ cells refer to the reproductive cells, specifically sperm and eggs, which undergo meiosis to form gametes. This process reduces the chromosome number by half, ensuring that when fertilization occurs, the resulting zygote has the appropriate diploid chromosome number.

In contrast, somatic cells, muscle cells, and nerve cells are all diploid, containing two sets of chromosomes, one from each parent. This paired arrangement is essential for maintaining genetic stability and facilitating normal cell function, growth, and reproduction in these types of cells.