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