Why Is Lipid Diffusion an Important Mechanism for Drug Absorption

Why is lipid diffusion an important mechanism for drug absorption?

A) Many epithelial membranes must be crossed if a drug is to distribute in the body and reach its target organ.
B) Epithelial cells do not have lipid membranes,so a drug must be water-soluble to diffuse across such a membrane.
C) It is directly related to the proportion of a drug that reaches the systemic circulation.
D) Lipid diffusion has no importance in drug absorption because the body has very few epithelial membranes drugs must cross.