Explanation:
In the sentence, the words “expected” and “only” imply that the data received from the spacecraft exceeded scientists’ expectations. Therefore, the words that fill the blank
should describe a reaction to results that are better than hoped for, and the choices “thrilled about” and “elated by” both express such a reaction. The scientists may well
also have been eager for, or keen on, the information, but their eagerness is not well explained by the unexpectedness of the information.
Thus, the correct answer is thrilled about (Choice C) and elated by (Choice E).
It was surprising when I understood that the verb "to thrill" means "to excite or please sb very much." This is an elementary word and I never looked up in the dictionary before, because I have always been sure that Thriller Movie is a frightening movie:)). So, I chose keen instead of thrilled. However, with the wealth of information after twelve years from far distances in solar system, I believe that scientists should be keen on the unknown information rather than thrilled.