Answer:
mitosis
Step-by-step explanation:
Mitosis is the type of cell division that the organism uses to grow. It increases the numbers of cells by proliferation, meaning the organism can grow larger.
Meiosis is a specialized type of cell division that creates gametes, which fuse to form the zygote.
Fertilization is the process through which the gametes fuse to form the zygote.
Differentiation is when cells become increasingly specialized to perform their function. Cells will differentiate slightly later in this process to form the different structures in the embryo.