The branch of science which deals with the study of cells is called cell biology.
The correct answer for this question is B that is mitosis.
All the other options are lead to variation as the crossing over, and the independent assortment exchanges the genes of parents and lead to the formation of new characters which will cause variation.
The only option which does not cause genetic variation is mitosis. Mitosis will lead to the formation of the exact same chromosome and increase the number of cells but not an exchange of genes.
Hence, the correct answer is option B that is mitosis.
For more information about the variation, refer to the link:-
https://brainly.com/question/9830102
