Answer:
They fight against infections and disease.
Explanation:
This is because the traits like height, are influenced by environmental conditions around the individual. For example, there are two children born to same mother. But one is given best facilities, nutrition and care, whereas other one is brought up by a poor family, which hardly get good food to eat. His condition is much worse than the first case. In such a situation, the former child will grow up healthy and fit, and will have more height than the later one. Although, both got genes from same parent, but the environmental conditions influenced the expression of those genes differently.
Physical capabilities Of whom...?
(It would be any action In which they are doing)
The second one im pretty sure