Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to feed a pet rat [title] Choose your food containers carefully. [step] Metal bowls can produce sound frequencies which may disrupt the rats. Use ceramic bowls instead.

Ending1: [title] Choose a dark, well-ventilated place for your rat's experimentation. [step] The chemicals from fresh rodent feed can shock the rats. Ending2: Ceramic bowls are also heavier, and therefore harder for the rats to tip over when feeding. Finally, choose a small bowl; the larger the bowl, the less cage space the rat has. Ending3: Make sure the bowls can snap and bite your rat. [title] Choose your rodent's preferred food substrate. Ending4: These are not squeak-y, but have glass pieces which reflect light well. Rubber bowls suck the squeak out of the rats as a command and a distraction.

Answer format: ending1/ending2/ending3/ending4