Final answer:
The production of an adult animal from a zygote involves primarily mitosis, which is the cell division process that creates identical cells, and differentiation, where cells become specialized. Option 2.
Step-by-step explanation:
The process responsible for the production of an adult body from a zygote in animals is mitosis. After fertilization, which is the fusion of haploid gametes to form a zygote, the single-celled zygote undergoes numerous rounds of mitosis.
Mitosis is a type of cell division that results in the generation of multiple identical cells from the original cell. These cells will continue to divide and differentiate to form various organs and body systems in the developing animal, which is a part of embryonic development.
Alongside mitosis, differentiation is also a critical process, where cells become more specialized in their function as they form different tissues and organs.
The complexity of this process is regulated by mechanisms in the organism that ensure the proper formation and function of various body parts.
It is important to note that while mitosis increases cell number, differentiation gives cells their distinct characteristics that contribute to the formation of a complex multicellular organism.
Just to clarify further on other terms mentioned in the question, fertilization is the process that starts everything off by combining the sperm and egg to form the zygote. Meiosis is the process of creating haploid gametes used in sexual reproduction.
And differentiation is part of the later development where cells specialize and take on different roles.
So Option 2 is correct.