What's in a Name?

Question

Pluto was discovered in 1930. It was named after the Roman god of the dead. For 76 years, it would be considered the ninth planet in our solar system. As scientists began to learn more about heavenly bodies, they began to refine the definition of "planet." In 2006, Pluto lost its title. Many scientists now refer to Pluto as a "dwarf planet."
Pluto was always the odd planet out, which led scientists to question its "planet status" from the beginning. For example, Pluto is a small orb with an icy surface. It follows an elliptical orbit that does not match the other eight planets' paths. Scientists have pointed out these differences for decades, but discoveries in the 1990s made the differences more significant. Scientists discovered other small, icy worlds called Kuiper belt objects (KBOs) located near Pluto. The International Astronomical Union felt that Pluto shared more in common with the KBOs, so it developed the new "dwarf planet" category. However, some scientists do not like the new category and refuse to acknowledge it.
5
What is the passage mainly about?
A.
Pluto was changed from "planet" to "dwarf planet."
B.
Pluto was named for the Roman god of the dead.
C.
Planets should follow elliptical orbits around the sun.
D.
Scientists have found KBOs in the solar system.

Answer 1

A. Pluto was changed from "planet" to "dwarf planet."

The passage primarily focuses on the classification change of Pluto from being considered a planet to being designated as a dwarf planet, explaining the reasons behind this shift.