This is a tricky question. It could be either a) or c), even b)!
When we're talking about the mind-body connection we're usually referring to the fact that our "mind" - which is basically our brain with it's neuronal connections and different neurotransmitters and hormones that influence how we think, feel, what we do, how we respond, behave etc. is related to our "body". When talking about our "body" in this case, we're usually talking about our observable behavior and what we can observe/feel for ourselves.
So because of this, we could say a) or c) are most probable, because the actual connection we're talking about is sort of a "model" that helps us understand this relationship, so I would opt for C., but A could be correct as well!
I suggest discussing this question in detail with your teacher!
