Which of the following describes one of Galileo Galilei's contributions to the development of the concept of gravity? a. He conducted experiments with balls and inclined planes.
b. He theorized that Earth was at the center of the universe.
c. He theorized that planets move around the Sun in an elliptical pattern.
d. He calculated a value that is currently known as the gravitational constant.

The correct option is;

c. He conducted experiments with balls and inclined planes

Explanation:

The inclined plane experiment conducted by Galileo Galilei was one of his most important experiments.

The experiment consisted of a grooved board with which a small metal ball is rolled down in, so as to analyze the held Aristotelian ideas about motion.

In the experiment, the focus was on acceleration, a concept that the previously held ideas about motion

double the distance = divide strength by 4

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.