What would happen to animal cells if they had cell walls like plant cells ?

Well if you mean animal cells having a rigid cell wall like that of plant cells a few things would happen: ... Cells would not be able to transport material in and out of the cell as easily with a cell wall (endocytosis and exocytosis especially would be hampered).

If an animal's body were made of plant cells, the animal would be very stiff and unable to move easily.

the correct answers are -

a) homeostasis

b) immunity

c) reproduction

d) growth and development

reason -

the endocrine system (produces and secretes hormones) is a vital system as it regulates the homeostasis by regulating the cell activity in the body. the endocrine system releases relevant hormones during specific time period in the blood which are then   transported across the blood , this not only maintains the chemical physical balance in our body but also regulate the vital functions of body such as growth, reproduction, and immunity