The answer to your question is A. You are correct
Answer:
The third line of defence against pathogenic invasion is the adaptive immune response, which has two key qualities: It is specific (it can differentiate between specific microorganisms and respond accordingly) It is adaptive (it can produce a heightened response upon re-exposure - in other words, it has memory)
Explanation:
The cytoskeleton of a cell allows the cell to be flexible. Our human skeletons allow <em>us </em>to be flexible.
B.) A dog walks to a stream and drinks when it gets thirsty
would have to be your answer..