Explanation:

- Section 311 of the CrPC empowers the court to summon any person as a witness at any stage of inquiry, trial, or other proceedings.

- This can be done on the application (motion) of the prosecution, if they believe a witness is important.

- Similarly, the defence can request the court to call or recall a witness if necessary for their case.

- Importantly, the court also has the suo motu (on its own) power to summon or recall any witness if it believes their evidence is essential for justice.

- Hence, all the options stated (Options 1, 2, and 3) are true—the court may act on prosecution's motion, defence's motion, or on its own initiative.

- Option 4: All the above is correct.