Yes, they can benefit an organism. That is why evolution works
Answer:
I would say one or more cells.
Explanation:
Unicellular organisms like bacteria contain one cell.
A multicellular organism, like us humans, contain many cells.
Therefore, all other options can be ruled out as living things can have one cell, or many cells.
It should have the shape number 2.
The substance A has a region that will bind to the nerve cell Y.
The drug developed that's going to block the substance A, will have to have a region that is complementary to the substance A. If those two regions get linked the substance A will have nowhere else to bind.