Ans. is 'a' i.e., Topical retinoids o Topical retinoids are the best comedolytic agents.Catagories of acne vulgariso Each category (Non-inflammatory, inflammatory and nodulocystic) can be further divided into:-i) Mild - Less than 10 lesionsii) Moderate - 10-25 lesionsiii) Severe - More than 25 lesions.Guidelines of management of acneo Step 1 - For mild acne (< 10 lesions):-# Topical therapy is used. Combination therapy is the best. Benzoyl peroxide - erythromycin gel plus topical retinoids combination is used. Topical erythromycin-Benzoyl peroxide gels are applied during the day; topical retinoids are applied in the evening.o Step 2 - For moderate acne (10-25 lesions), and mild acne not responding to topical therapy:-# An oral antibiotic is added to the above topical regimen. The most effective antibiotic is minocycline or doxycycline. In females, moderate acne can be controlled with high doses of estrogens combined with progesterone or antiandrogens.o Step 3 - For severe acne, nodulocystic lesions, large nodular lesions, and moderate acne not responding to oral antibiotics (Recalcitrant acne):-# Isotretinoin is the drug of choice Isotretinoin is the single most advance in the management of severe acne. It inhibits sebaceous gland function and keratinization and is very effective. Oral isotretinoin leads to complete remission in almost all cases. If the patient cannot afford isotretinoin, dapsone is a useful alternative. Intralesional steroids can help in the management of cysts and nodules. If there are signs of androgen excess, antiandrogens (cyproterone acetate) can be used with estrogen.