Answer: D
Explanation: just took the quiz
It is a Secondary source because it is conducted by the conductor.
The
molecules which move large molecules into and out of the cell are known as
membrane transport proteins-transporters.
<span>Their
function is to move all the molecules that are not capable to pass via passive
diffusion. So, transporters are involved in the movement of ions, small
molecules, or macromolecules, such as another protein, across a membrane.
Transporters are integral transmembrane proteins and can be categorized as channels
or carriers. These proteins assist in the movement of molecules by facilitated
diffusion or active transport.</span>
I am not sure on this but I think it would be B) sorry if this is not the correct answer
