What is the purpose of the third paragraph in the passage?Our Amazing Solar System

by NASA and STScI (adapted excerpt)

Very little was known about Neptune and its atmosphere until Voyager 2 arrived at the planet in 1989. Voyager revealed a banded cloud structure and a storm that was called the Great Dark Spot. Neptune's axis is tilted similar to Earth's. Neptune therefore exhibits seasonal changes. However, the seasons on Neptune last for decades, not months as on Earth. In fact, Neptune has only completed one orbit of the Sun since its discovery in 1843. It is remarkable that Neptune exhibits any evidence of seasonal change at all, given that the Sun, as viewed from the planet, is 900 times dimmer than it is from Earth. Still, Hubble, a deep space telescope, has been able to observe such changes.

Hubble's near-infrared capabilities allow the telescope to observe high-altitude clouds on Neptune that are useful for tracking seasonal changes. In fact, Hubble images taken in the late 1990s showed that cloud bands on Neptune were getting wider and brighter were considered the first observational evidence that the planet undergoes a change of seasons.

In 2002, astronomers using Hubble noted that the abundance of high-altitude clouds increased the planet's brightness from observations made in the late 1990s. Astronomers consider this brightness increase a sign of seasonal change. Hubble studies show that Neptune has a nearly constant brightness at low latitudes (near the equator). This supports the idea that the observed changes are seasonal in nature, because seasonal effects would be minimal near the equator and most evident at high latitudes.
A.
to introduce the idea that Neptune is similar to other planets in the galaxy
B.
to demonstrate how scientists were able to conclude that Neptune has clouds like Earth
C.
to suggest that Neptune is similar to Earth in terms of weather patterns
D.
to prove how scientists were able to confirm that Neptune has recurring weather