ICAM-1's roles in adhesion, viral attachment, and membrane structure

Steps:

• Statement 1 is true: ICAM-1 mediates cell-cell adhesion, so blocking it with a drug would also prevent cells from attaching to each other.
• Statement 2 is true: Viral attachment requires specific binding, so ICAM-1's structure must complement viral coat proteins like a lock and key.
• Statement 3 is true: As a transmembrane protein, ICAM-1 embeds in the lipid bilayer, requiring hydrophobic regions for stability.
• All three statements hold, confirming option A.

Why A is correct:

• ICAM-1 functions as both an intercellular adhesion molecule and a viral receptor, with its structure governed by biochemical principles of specific binding (statement 2) and membrane integration via hydrophobic interactions (statement 3), while its adhesion role implies blocking effects (statement 1).

Why the others are wrong:

• B omits statement 3, but hydrophobic parts are essential for membrane proteins.
• C omits statement 2, but complementary structures enable specific viral binding.
• D omits statement 1, but ICAM-1's adhesion function means blocking it affects cell attachment.

Final answer: A