Answer:
A secret. When you have a secret, you want to tell other people, but when you do, it's no longer a secret.
It is the natural/genetic ability of an organism to avoid or repel attack by biotic agents (pests etc.) or to withstand the effects of abiotic agents example (chemicals).
The neuron releases chemical messengers. Otherwise, there would be no 'signal transduction' in the postsynaptic cell. So, your answer is B.
12/44 = 0.2727
(X100)
= 27
( therefore the percent mass of carbon in carbon dioxide is 27%)