Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to teach a dog to tell you when he wants to go outside [title] Hang a bell by the door. [step] Make sure the bell is within the dog's reach and is loud enough that you will hear it even if you are not in the same room. It's also important that it be durable enough that your dog won't break it.

Ending1: You can buy bells with hollow hooks or find metal ones at your local hardware store. [substeps] If the bells are lost somewhere, hide them in a pocket or in a hidden room where no dog could find them. Ending2: [substeps] For this trick, stand in front of the bell, but don't sit in front of it. Cover it with your hands, as if it were a leash or blanket, and then start walking in the direction the sound will come from. Ending3: [substeps] You can also use a wireless doorbell, as long as your dog will be able to push to button. If your dogs seems afraid of the sound of the bell, try dampening it with some tape to make it quieter. Ending4: [substeps] Make sure the bell is positioned above the dog's head. Not only does that discourage the dog from jumping up to get it, but if the bell's head is above the dog's heart, this can result in the dog giving up.

Answer format: ending1/ending2/ending3/ending4