A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?

A human cell in prophase of mitosis contains 46 chromosomes with 2 chromatids each, which counts for a total of 92 chromatids.

Explanation:

In prophase, the first stage of mitosis (cell division), all 46 chromosomes have their chromatids duplicated. This is of key importance for the mitosis to happen correctly since these duplicated chromatids will separate and be part of the nuclei of the daughter cells that will be produced when the division ends. This way, each new cell will have an entire set of 46 chromosomes with 1 chromatid each.