Understanding the Question:
The question asks which listed group of three drugs belongs to BCS class III, one of the four Biopharmaceutics Classification System categories.
Key Concept:
BCS class III covers drugs with high aqueous solubility but low intestinal permeability, meaning the drug dissolves fast but crosses the gut wall slowly, so absorption is the rate-limiting step rather than dissolution.
Checking Each Option:
Acyclovir, atenolol and captopril all dissolve easily in water yet are known for limited and variable oral absorption because they cross the intestinal membrane slowly, matching the high-solubility, low-permeability pattern exactly.
Taxol is a poorly water-soluble drug with fair permeability, closer to class II, so pairing it with aspirin, a class I drug, does not fit class III.
Aspirin and paracetamol both dissolve and permeate well, the hallmark of class I, so this trio does not represent class III either.
Chloroquine, diltiazem and metoprolol are lipophilic and cross membranes efficiently, keeping them out of the low-permeability class III group.
Final Answer:
Acyclovir, atenolol and captopril are the set that fits the high solubility, low permeability profile of BCS class III.