The doctor … him to take his medicine regularly.

Analyze the question: The sentence needs a verb in the correct form to fit "The doctor ____ him to take his medicine regularly." The action is completed (the doctor gave the advice), so we need a past tense verb.

Explain the concept: "Advise" and "advice" are often confused:

• Advice is a noun (the guidance given). Example: "He gave me good advice."
• Advise is a verb (the act of giving guidance). Example: "She advised me to rest."

The past tense of "advise" is formed by adding -d, giving advised. "Adviced" is a common misspelling and does not exist in standard English.

Step-by-step solution:

1. The gap comes after the subject "The doctor", so we need a verb. • This rules out D (advice), which is a noun.
2. The sentence is in the past tense (the doctor already gave the instruction). • This rules out C (advise), which is the base/present form (we would need "advises" for the present anyway).
3. Between A (adviced) and B (advised), only one is correctly spelled. • "Advise" already ends in -e, so we add only -d: advise → advised. • A (adviced) is a wrong spelling.

Complete sentence: The doctor advised him to take his medicine regularly.

Correct answer: B. advised

Exam tip: Remember the C/S rule: advice (with a c) is the noun, and advise (with an s) is the verb. A quick check is to swap in a similar pair: practice (noun) / practise (verb) in British English. Also, "advise someone to do something" is a common JAMB pattern, so watch for the verb form after the subject.