Which of the following medications is considered a controlled substance classified as Schedule V when mixed with other antitussive medications?

Choice A rationaleDiphenhydramine is an antihistamine used to relieve allergy symptoms.Choice B rationaleCodeine is a narcotic pain reliever and cough suppressant classified as a Schedule V controlled substance when combined with other antitussive medications.Choice C rationaleBenzonatate is a non-narcotic cough suppressant that numbs the throat and lungs.Choice D rationaleGuaifenesin is an expectorant and not a controlled substance.