Answer:
Body constantly break downs and repair or rebuild its own cells and tissues which is lead to the need for the protein. In under different conditions like intense physical activity or sickness or injury can also result in requirement of protein as in diet.
All these process to occur one need to consume enough protein. Excessive protein than requirement for cell or body requirement will normally metabolize to produce amino acids and energy.
Thus, the correct answer would be - it will provide essential amino acids for producing different hormones and building and repair cells and tissues and energy.