The passage focuses on comets primarily in terms of their Why does the author mention the Giotto probe in paragraph 3?

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问题 The passage focuses on comets primarily in terms of their
Why does the author mention the Giotto probe in paragraph 3?

选项 A、It had a relatively small and inconspicuous nucleus.
B、It was very similar to an asteroid.
C、It was covered with an unusual black dust.
D、It provided visual evidence of the makeup of a comet’s nucleus.