It's needed to consider that we have two kinds of cells: somatic cells (which have 2 chromosomes inherited from our parents; 2n), and sexual cells (which have only one chromosome, inherited only from one of our parents; n). This is crucial to understand that somatic cells, whose genetic information we do not inherit, and sexual cells, whose genetic information we do inherit, differ in how they divide themselves. The first one, although they divide themselves, they can't pass a mutation to the offspring, while sexual cells can do, or the B option, which states "cells that are produced when the mutant cell divides".
