Answer: B) Everyone was having a wonderful time at the party.
Explanation: In a sentence active voice is when the subject is the one who performs the action of the verb, and the direct object receives the action (for example, in the sentence "the boy eats the cake" the subject is the boy and the direct object is the cake). Passive voice is when the direct object is the subject of the phrase (for example: the cake is being eaten by the boy). From the given options, the one that is in active voice is option B, because the subject is "everyone" and it is performing the action of the verb, while the direct object "a wonderful time" is receiving it.