PSAT Reading Question 565: Answer and Explanation

Question: 565

The primary purpose of the second paragraph (lines 30–53) in the passage as a whole is to

• A. discuss the physical definition of elliptical eccentricity.
• B. provide scientific justification for the rarity of Halley's predictable visibility.
• C. give historical evidence of human observation of Halley's velocity.
• D. differentiate Halley from other celestial bodies, such as planets and meteors.

Correct Answer: B

Explanation:

(B) The author uses this paragraph to give scientific reasons, such as Halley's unusually elliptical orbit, as to why Halley's Comet is a uniquely observable comet. The other options do not give the "primary" purpose of the paragraph, just minor things that are mentioned.