Explanation:

- Standing Offer: A standing offer is ongoing and can be accepted at different times over a period. It's like an open invitation to treat, remaining open for acceptance until revoked. Correct Answer: Option 1, Standing Offer.

- Specific Offer: This is directed to a specific person or group and can only be accepted by them. It does not remain open for general acceptance over time.

- Express Offer: This is clearly stated, either verbally or in writing, leaving no room for ambiguity about the terms.

- Implied Offer: This is not directly stated but inferred from actions, circumstances, or conduct. It's based on the behavior of the parties involved.