I'm pretty sure it's the last one; Everyone was having a wonderful time at the party, because the present tense helps it feel more active.
Answer:
Guppies can live with other peaceful fish in aquariums, but piranhas should only be kept in tanks with other piranhas because piranhas typically eat other fish.
Editorial because you can be biased at weather the news or a recap
OR is the coordinating conduction in the sentence
