Step 1: Understanding licensed premises.
A chemist and druggist is a premise licensed to sell drugs, where a qualified person (typically a registered pharmacist) is in charge, and the drugs are sold without compounding. Such establishments are required to follow certain regulations under the Pharmacy Act.
Step 2: Analyzing the options.
(1) Drug store: Incorrect, a drug store is a general term and may not necessarily require a qualified person.
(2) Drug vendor: Incorrect, this refers to someone selling drugs without necessarily having the proper licensing or qualifications.
(3) Chemist and druggists: Correct — This is the licensed premise where drugs are sold by a qualified pharmacist, and no compounding takes place.
(4) Manufacturing unit: Incorrect, manufacturing units are involved in the production of drugs, not their sale.
Step 3: Conclusion.
The correct answer is (3) Chemist and druggists.