This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to clean your dog's toothbrush
Use a separate toothbrush for each dog.
After brushing your dog's teeth, rinse the toothbrush under warm water. Remove any toothpaste, food particles, and debris from the toothbrush with your thumb.

OPTIONS: (i). You can also use a toothpick to remove smaller particles. Rinse the toothbrush after each use. (ii). Taking the brush into hot water can potentially damage the toothbrush. Make sure your dog will use a seat. (iii). Gently wipe down the bristles with the toothbrush until all traces of toothpaste are gone. If you use a toothbrush with a plastic handle, make sure to replace it before handling it again. (iv). You do not want to leave any residue in the brush while it is being cleaned. This method can be very messy and requires a regular brush.
The answer is:
(i).