The police have … a warning to all residents of the area.

Analyze the question: This is a phrasal verb question. We need the phrasal verb that means "to issue or release" a warning or statement.

Explain the concept: The verb "put" combines with different particles to give different meanings:

• put on: to wear, or to stage a show (e.g. "put on a play")
• put in: to insert, or to submit (e.g. "put in an application")
• put off: to postpone, or to discourage (e.g. "put off the meeting")
• put out: to extinguish, or to issue or publish an announcement (e.g. "put out a statement")

Step-by-step solution:

1. The sentence says the police did something with "a warning" directed at all residents.
2. A warning is a public notice, so the verb must mean "issue" or "announce."
3. Testing each option: • "put on a warning": wrong, because it does not mean to issue a warning. • "put in a warning": wrong, because it suggests inserting something, or submitting a request. • "put off a warning": wrong, because it would mean to postpone the warning, which makes no sense here. • "put out a warning": correct, because it means to issue or release a warning publicly.

Answer: D. put out

Tip: Link "put out" with communication words such as a statement, a warning, a notice, a press release, a bulletin. For example, "The ministry put out a statement." For fire, "put out" also means extinguish, so the context of a warning tells you it means "issue."