Question

does the sentence need a comma? pick the right option. everett ross will train his pet dinosaur today, or tomorrow.

Explanation:

In a compound - sentence joined by a coordinating conjunction like "or", a comma is used to separate the two independent clauses. Here, "Everett Ross will train his pet dinosaur today" and "tomorrow" (the implied "he will train it tomorrow") are parts of a compound - like structure.

Answer:

Yes, the sentence needs a comma as it is.