Question

which sentence should replace sentence 19 to bring the third paragraph (sentences 14–19) to a more effective close?
① in the end, the international astronomical union decided that it was, and pluto was reclassified as a dwarf planet.
② in the end, scientists had a lot of questions and tried to find reasonable answers to these questions.
③ in the end, it was confirmed that pluto was in the kuiper belt from the other objects being studied.
④ in the end, many people had opinions, and they shared their opinions with the other astronomers.

Explanation:

To close the paragraph (sentences 14 - 19, likely about Pluto's classification), the best option should relate to the resolution of Pluto's status. The first option states that the International Astronomical Union decided Pluto was reclassified as a dwarf planet, which effectively concludes the topic of Pluto's classification. The other options either talk about general scientific questions, Pluto's location (not the main focus of the paragraph's closure), or people sharing opinions, which don't provide a strong conclusion about Pluto's classification.

Answer:

A. In the end, the International Astronomical Union decided that it was, and Pluto was reclassified as a dwarf planet.