In spite of their name, the prairie dog is not a dog at all

Hi ,
that is true..in this question the only reason to eliminate option B is INSPITE OF is wordier.
inspite of and despite almost have the same meaning.

moreover

In spite of vs Despite
In spite of - used to express the idea of contrast.

A). In spite of - is used as a preposition. In spite of + noun means almost same as although + clause.

e.g - We went out in spite of the rain. ( = .... although it was raining.)

B). In spite of is the opposite of because of .

e.g - She passed her exams in spite of her teacher. => (She had a bad teacher)

She passed her exams because of her teacher. => (She had a good teacher).

C). In spite of cannot be followed directly by a that - clause. Instead we can use in spite of the fact that

e.g - He is a good company in spite of the fact that he talks all the time.

Note - In formal English, despite can be used in the same way as in spite of.

e.g

john went on working in spite of feeling unwell.-- Correct
john went on working despite feeling unwell.-- Correct

hope it helps