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

How to introduce an older cat to a new dog
Start by keeping the animals apart.
When you're introducing a new dog to an older cat, you'll want to plan their introduction carefully. Though they're sharing your home, male sure that they're confined to their own spaces at first.

Choose from:
[A]. If an older or older cat can fit in a new room, a new dog may prefer the smaller house or be less likely to feel stressed about missing them than an older or older cat. Make sure the room you get them into feels like home..
[B]. Let them spend time in separate rooms or areas at first. Over time, gradually move into establishing a stronger bond with your new cat..
[C]. Allowing them time to adjust to each others' scents within your home will help them get used to each other. You'll want to prevent any direct contact until your new dog has had his vet checkup and is cleared of any contagious diseases or infections..
[D]. When you do introduce two new dogs, keep the existing dogs separate and move all the cats away from each other. This provides enough time to establish a good environment and support the introduction..
The answer is:
[C].