Chromosomes
Germline cells are haploid, i.e they have only one copy of each gene, unlike somatic cells, which are diploid, that is, they have two copies of each gene. So, as in human skin cells, which are somatic cells, there are 46 chromosomes, the egg cell, which belongs to the germline, has 23 chromosomes.
Therefore, the correct answer to this question is option D.