Answer:
The sentence that contains an appositive phrase is B. The safari stopped at an oasis, a moist, fertile spot in the desert.
Step-by-step explanation:
An appositive noun -or noun phrase- provides further information about the noun or noun phrase in apposition to it to define it or identify it. It could also be used to rename the noun right beside it. As appositive nouns or noun phrases are often nonrestrictive, they are placed between commas or are preceded by a comma if they are at the end of the sentence, like in option B. The safari stopped at an oasis, a moist, fertile spot in the desert.