19. Which choice most clearly suggests that Williams is not the only astronaut who has worked at the ISS?
Your Answer is
Correct Answer is B
Explanation
The question stem requires "to express that she is not the only astronaut working in the ISS", and only contribute to ongoing research "to contribute to continuous research", which means that what she has done is only part of it. Complete, devote herself to, work on, cannot express this meaning.