The correct answer is option B, that is, reduction in the number of chromosomes per cell.
Meiosis refers to a unique kind of cell differentiation, which minimizes the number of chromosomes by half, forming four haploid cells, each genetically different from the parent cell from which they originated.
This procedure takes place in all the sexually reproducing single-celled and multicellular eukaryotes, including fungi, animals, and plants. In meiosis, the replication of DNA is succeeded by two rounds of cell differentiation to generate four daughter cells, each with half the number of chromosomes as the main parent cell.