Which of the following best demonstrates the principle of complementarity of structure and function?

The correct answer for this question is this one: 
" Bones can support and protect body organs because they contain hard mineral deposits. "

These are the following choices:
a) The heart and blood vessels circulate blood continuously to carry oxygen and nutrients to all body cells. 
b) Bones can support and protect body organs because they contain hard mineral deposits. 
c) Atoms, the tiny building blocks of matter, combine to form molecules such as water and proteins. 
d) The liver, the brain, blood vessels, and stomach are each responsible for a necessary activity that no other organ can perform.