Which of the following is an example of a dosage form?

A dosage form refers to the physical form in which a drug is produced and dispensed, and it plays a crucial role in the drug's delivery and bioavailability. In this context, a tablet is a solid dosage form that typically consists of active ingredients as well as excipients, which help in the formulation and stability of the drug. Tablets are designed for oral administration and are one of the most common forms of medication, allowing for precise dosing and ease of use.

The other options represent different concepts within pharmacy and pharmacology. A therapeutic agent relates to the class of drugs or medications used for treatment, but it is not a physical dosage form. An active ingredient denotes the specific component in a drug that is responsible for its therapeutic effect, rather than the manner in which the drug is delivered. A prophylactic refers to a treatment aimed at preventing disease, but again does not refer to a specific dosage form. Therefore, the only option that correctly identifies a dosage form is the tablet.