Step 1: Understanding the Concept:
This question tests the correct verb tense to describe an action happening at the moment of speaking.
Step 2: Detailed Explanation:
The phrase "Keep quiet" indicates that the speaker is requesting silence because an action is currently in progress.
The present continuous tense (am/is/are + verb-ing) is used to describe actions happening right now.
The structure of the sentence is "we are ........", which is the setup for the present continuous tense.
- (A) listen - base form, incorrect.
- (B) listened - past tense, incorrect.
- (C) will listen - future tense, incorrect.
- (D) listening - present participle, correct form for present continuous.
Step 3: Applying to the Sentence:
To complete the present continuous structure "we are...", we need the present participle 'listening'. The full sentence becomes "we are listening to the radio."
Step 4: Final Answer:
The correct verb form is listening.