If you're referring to one mammal in particular, then it should be the mitosis of body cells. Body cells do not perform meiosis as that is only for gamete production, therefore, it only happens in sex cells. In contrast, body cells will create identical copies of themselves so the organism can grow through mitosis. I hope that helps!
Remember that Mitosis comprises the somatic cells that is vital for individuals growth. while Meiosis comprises the division of two gametes,which the cell genetic's information.
eliminate 1,3, 4 because meiosis is for somatic cells. also it is not responsible for growth.
the best answer should be number 2, mitosis of body cell it carry out to develop complex organisms as a means of maintaining the organisms.
