Question

Graduate students Delia Marcus and Pedro Salazar explain that astronomy is the study of space and the physical universe, and it may be challenging to understand its appeal to young scientists. Marcus remarks, "What other branch of science gives you the chance to visualize the origins of the universe?" Salazar concurs, "We astronomers are at the forefront of understanding the very mechanisms that make the cosmos possible." To confirm their points, Marcus and Salazar interviewed several experts in the field, including author J.D. Matthews and astrophysicist Michael Davies, who agree with their assessment. Matthews comments, "Understanding how our own solar system works is just one piece of the puzzle. There are countless other solar systems like ours across the universe." Davies further elaborates, "This begs the question, when—not will—we find a similarly habitable planet like our own?"
Question
Use the passage to answer the question.

Which word describes the tone of the last sentence of the passage?

(1 point)
Responses

worried
worried

formal
formal

optimistic
optimistic

assertive
assertive

Answer 1

assertive

Explanation: The sentence shifts from "will" to "when," expressing certainty and a strong claim (asserting it will happen), so the tone is assertive rather than worried, formal, or merely optimistic.