Explanation:

- X intended to cause Y's death by using a child to mix poison. This shows a clear intention to kill Y.

- Option 1: No offence - This would not be correct; X had intent and acted upon it.

- Option 2: Abetment of murder - This involves encouraging someone else to commit murder. Here, X used a child to accomplish his goal.

- Option 3: Murder - Using a child to directly act on an intention to kill reflects direct responsibility, making it murder.

- Option 4: Culpable homicide not amounting to murder - This is when there’s no intent to kill, which is not the case here.