Molecules a and b come in contact with the cell membrane of the same cell. molecule a passes through the membrane readily, but molecule b does not. which statement could describe molecules a and b?

Molecule A is a simple sugar or amino acid, while molecule B is a starch or protein.

Explanation:

Molecule A, as a simple sugar or amino acid, consists of small molecules which can readily pass through the cell membrane, while Molecule B, as a starch or protein, consists of large molecules, thus, can't pass across the cell membrane.

This is the reason why the cell membrane is considered to be selectively permeable.

the answers are a and c