Explanation:

- Committal proceedings under Section 209 of CrPC refer to the preliminary process in criminal cases to decide if there is sufficient evidence to justify a trial.

- Option 1: Aid in investigation

- Committal proceedings do not directly aid in investigation. They occur after the investigation has gathered necessary evidence.

- Option 2: Inquiry

- An inquiry evaluates if the collected evidence is enough to proceed to trial. This seems closest to the nature of committal proceedings.

- Option 3: Trial

- A trial is the stage where the actual guilt or innocence is adjudicated, unlike committal proceedings.

- Option 4: Either inquiry or trial

- Committal proceedings specifically serve as an inquiry, not a trial.

- Correct Answer: Option 2: Inquiry