What substance would have the slowest speed of passage across a selectively permeable membrane?

Large polar molecules

Cell membrane or plasma membrane is a semi permeable membrane. it is made of lipid bilayer. Only lipid soluble molecules and small molecules can pass through it. Ions and large polar molecules cannot pass through it. Non-polar molecules are highly permeable whereas, polar molecules are low permeable.

d is the answer

sorry if its wrong!

the truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey.