Explanation:

- Option 1: No Offence

- X acted in good faith and based on a reasonable belief that Z was committing a murder.

- The law allows individuals to apprehend someone committing a serious crime like murder.

- Correct Answer: X is not guilty of any offence as he acted lawfully under mistaken belief.

- Option 2: Wrongful Restraint

- This involves preventing a person from proceeding in a direction they have a right to go.

- X's actions were aimed at lawful apprehension, not mere restraint.

- Option 3: Wrongful Confinement

- This implies confining a person in a space without legal justification.

- X did not confine Z; he intended to bring Z to authorities, which the law allows in such cases.

- Option 4: Assault

- Assault involves causing apprehension of offensive contact.

- X did not intend to cause harm but to prevent a crime.