Final answer:
The correct answer to the question is d. suppository, which is a solid dosage form designed to melt at body temperature when inserted into a body orifice.
Step-by-step explanation:
A solid dosage form that has the active ingredient placed in a water-soluble base that will melt at body temperature is known as a suppository. This form of medication is designed for insertion into a body orifice where it dissolves or melts, providing a local or systemic effect. An ointment is a semisolid dosage form used for topical application and not designed to melt at body temperature. A cream is a semi-solid emulsion of oil and water used for application to the skin or mucous membranes, but does not necessarily melt at body temperature. A gel is a usually clearer semisolid preparation that may be used topically, often having a thicker consistency than creams but not designed to medicate through melting like a suppository. Therefore, the correct answer to the question is d. suppository.