Answer: A. All of the kittens are black with white paws.
Explanation: Subject-verb agreement is simply to use singular verbs with singular subjects and plural verbs with plural subjects. In the given sentence the subject is "all of the kittens" this is a plural subject, therefore, we need to use a plural verb to have a correct subject-verb agreement, from the given options, the only one that uses the correct conjugation is option A: All of the kittens are black with white paws.
One strategy you can use to determine the meanings of unknown words and phrases is to look at the context clues. Context clues might be something like a picture, words or phrases you already know, using what you know about the text already.
Hope this helps!