Complete with the correct pronoun: Is there going to be communication between _____ humans and those other life forms?

• A. we
• B. us
• C. I
• D. they

Answer: (B)

The main idea is pronoun case after a preposition. After a preposition like between, you need an object-form pronoun. In this sentence, the phrase goes with two groups in a relationship: us humans and those other life forms. “Between” requires the pronoun in its objective case, so the natural, correct form is us. Using we would be wrong here because we is the subject form, not the object form, and the sentence isn’t about the humans doing the action but about the relationship between the two groups. I is ruled out for the same reason, and they would need to be the object “them” if you were to use a different pronoun. That’s why the best choice is us.