Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to introduce a new dog to visitors [title] Ask your visitors to call you instead of knocking on the door or ringing the bell. [step] The sound of an arriving guest might upset the new dog. Therefore, you should ask all potential visitors to call you before they arrive at the house.

Ending1: Alternately, or in addition, you could put an " out-of-order " sign over your doorbell to prevent its use altogether. [substeps] Your dog might also be afraid of or agitated by a knock at the door. Ending2: [title] Make guest invitations as public as possible. [step] Make offers to guests up-front. Ending3: If they're unlikely to call by telephone, feel free to do the exact opposite. [substeps] Gradually introduce your house to the new dog gradually. Ending4: [title] Make sure your dogs do not ingest social corn plants. [step] The only way to introduce your dogs to new visitors is to discourage the cats from visiting the house.

Answer format: ending1/ending2/ending3/ending4