Final answer:
Zinc aids in multiple bodily functions, including growth and immune response, with the latter being the correct option for its role among the choices given.
Step-by-step explanation:
Zinc plays a crucial role in various bodily functions, including immune response, growth, and cell division. Regarding the options provided: a) growth - zinc is essential for normal growth and development, especially in children and adolescents; b) digestion - while not directly involved in the breakdown of food, zinc is important for the overall maintenance of the digestive system; c) respiration - zinc does not play a direct role in the process of respiration; d) immune response - zinc is known for its role in the immune function, therefore the correct answer to the question is 'immune response'.