Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to diagnose respiratory problems in gerbils [title] Examine your gerbil's eyes and nose. [step] When a gerbil has a respiratory problem, a liquid discharge will start coming out of its eyes and nose. This discharge may be thick and mucus-like, indicating an infection.

Ending1: Excessive condensation may also indicate a respiratory problem. [title] Keep your gerbil up to date with their vaccinations. Ending2: [substeps] Your gerbil's eyes may also be half closed and look dull. A healthy gerbil's eyes would be fully open and bright with an alert-looking stare. Ending3: Your gerbil may also smell things other than its waste. [substeps] Make a fuss if you see fluid coming out of its eyes. Ending4: Observe your gerbil's eyes and nose to determine if it has gotten infected. [substeps] If your gerbil is not breathing, its nose may be more bloated than normal.

Answer format: ending1/ending2/ending3/ending4