Answer:
[tex]\boxed {\tt B. \ They \ move \ through \ tiny \ pores}[/tex]
Explanation:
Cell membranes are selectively permeable, which means certain molecules can pass in and out, but others cannot.
One factor is size. Small molecules can move through openings in the membrane, but bigger ones cannot pass and usually need assistance from carrier proteins.
Therefore, the best answer choice is B. They move through tiny pores
