Final answer:
During metaphase of mitosis, a cell with 18 pairs of chromosomes would contain 72 chromatids.
Step-by-step explanation:
The question asks about the number of chromatids present during the metaphase of mitosis, given that a cell contains 18 pairs of chromosomes immediately after mitotic cytokinesis. During metaphase, chromosomes align at the metaphase plate, and each chromosome consists of two sister chromatids attached at a centromere. Thus, for 18 pairs (or 36 chromosomes), there would be twice as many chromatids, meaning the correct answer is 72 chromatids.