I have linked an image of the question I need help with. For this question I have to put which definition is a carbon cycle, which one is a nitrogen cycle, and which one is a phosphorus cycle.

I know the middle definition is for the Carbon cycle. I think the first is phosphorus and the last is nitrogen.

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.