The system senses changes in the internal and external environment so that the body can adapt to the changes.
a.
nervous
b.
reproductive
c.
endocrine
d.
circulatory

The answer is either endorcrine or reporudctive, 

Body parts of unrelated organisms that serve the same function are examples of convergent evolution.
Convergent evolution is the phenomenon when the different species independently create similar features. Those features can be structures that have similar form or function. This happens because organisms have been adapted to similar environments or ecological niches.