An adolescent patient with moderate acne has begun a regimen consisting of combination clindamycin/benzoyl peroxide [BenzaClin] and tretinoin [Retin-A]. Which statement by the patient indicates understanding of this medication regimen? a. "I should apply the Retin-A immediately after bathing." b. "I should apply the Retin-A twice daily." c. "I should augment this therapy with an abrasive soap." d. "I should use sunscreen every day."