Explanation:

- General Offer:

- A general offer is made to the public at large, not to any specific individual.

- Any person who performs the required action can accept this offer.

- Example: A's advertisement fits as it invites anyone who finds the dog to claim the reward.

- Answer: Option 1 - General offer

- Specific Offer:

- A specific offer is directed to a particular person or group.

- Only the person or group to whom the offer is made can accept it.

- Example: An invitation sent directly to a named individual.

- Implied Offer:

- An implied offer is not explicitly made but inferred through conduct or circumstances.

- Example: Placing products on a store shelf implies they are for sale.

- Invalid Offer:

- An invalid offer does not comply with the essential elements needed to constitute a valid contract offer.

- Example: Offers made without the intention to create legal obligations.