The study of cells is called cell biology. There are two types of cells on the basis of the number and these are unicellular and multicellular.
The correct answer is option D which is haploid.
According to the question, in reproduction, meiosis help to divide the diploid cell into haploid for the formation of gamete.
Hence, the correct answer is option D.
For more information about the cell, refer to the link:-
https://brainly.com/question/10577996