His father served as a mercenary in the army?

Analyze the question: You need the antonym of "mercenary" as used in "His father served as a mercenary in the army."

Explain the concept: A mercenary is a professional soldier hired to fight for a foreign country or group, mainly for money rather than loyalty to a nation. So the opposite is a soldier who belongs to his own country's official, standing army, which is a regular soldier.

Step-by-step solution:

• A. preacher: a religious minister, not related to military service. It is not an opposite.
• B. regular: a soldier in a country's permanent, official army. This contrasts with a hired outsider, so it fits as the opposite.
• C. recruit: a newly enlisted soldier. This describes a stage of service, not hired versus national, so it is not the opposite.
• D. officer: a rank, which can be held by a mercenary too, so it is not the opposite.

Answer: B. regular

Tip: For vocabulary antonym questions, first define the word in your own mind ("hired soldier, fights for pay"), then look for the option that reverses the key idea. Here the key idea is "hired outsider," so the reverse is "official or regular soldier." Also remember that "mercenary" can mean "motivated by money" in general, but in this military context the "regular" contrast works best.