Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to make a clicker for dog training [title] Find a small aluminum jar lid. [step] The lid on a jar of baby food or the lid to a small mason jar will work. You want a lid that's around 2-3 inches (5-7.6 cm) in diameter.

Ending1: [title] Place several small balls of white food in a small bowl. [step] The balls of food will give your dog treats. Ending2: [title] Place the jar lid face down on a flat surface. [step] The underside of the jar lid should be facing up. Ending3: [title] Remove the lid and expose the food inside. [step] Once the lid is removed, you'll be able to see inside the jar. Ending4: [substeps] Make sure the lid is clean before you put the baby food or puppy food in. It needs to be as clean and free of dust as possible.

Answer format: ending1/ending2/ending3/ending4