Please no links. I really need help with this Biology question.

the correct answer is option d.

an appositive is a noun, noun phrase or noun clause which follows another noun or noun phrase in order to describe it or name it another way. they are usually used between commas, brackets or dashes.

the example sentence with the correct use of commas is the following:

her uncle, the man over there in the red shirt, owns the hardware store in town.

i'd have to say the answer is probable the second option "the geosphere interacting with the atmosphere"

answer an inhibitory neurotransmitter in the brain;