Question

summary
mercury
of all the things floating in space, planets are the most amazing.
one incredible thing about planets is that theres still so much to
learn. mercury is the smallest planet in our solar system. some
people think mercury is a small, unimportant planet, but theyre
wrong. just because its not much bigger than earths moon,
mercury is part of the balance of our solar system that allows for
life on earth. other planets help this too. mars is another
fascinating planet. its very much like a desert on mars. its the
planet closest to the sun, with daytime temperatures of 800
summarize the text. hint: leave out opinions. which
detail should be included?
mercury is the smallest planet in our solar system and the closest one to the sun.
the reason planets are so fascinating is that we are still learning more about them.
of all the things floating in space, planets are the most amazing.

Explanation:

To summarize the text (leaving out opinions), we need factual details. The first option states a fact about Mercury: it's the smallest planet in the solar system and closest to the sun. The second option is an opinion about why planets are fascinating, and the third is an opinion about planets being the most amazing. So the factual detail to include is the first one.

Answer:

A. Mercury is the smallest planet in our solar system and the closest one to the sun.