Explanation:

- Option 1: No offence

- A is intending to cause a miscarriage but administered a harmless substance.

- A didn't cause any harm or change the condition of the pregnancy.

- Answer: Correct.

- Meaning: If the substance was genuinely harmless, then there is no actual effect on the pregnancy, and thus, no criminal offence is committed.

- Option 2: Attempt to cause abortion

- The intent was to cause a miscarriage, but the action is crucial.

- Because the substance was harmless, it might not constitute a legal attempt.

- Option 3: Attempt to cause murder of unborn child

- Murder typically applies to born individuals, not unborn children.

- This option is not applicable in this context.

- Option 4: Culpable homicide

- Culpable homicide involves causing death.

- This doesn't apply as the action didn't result in death.