It might be an ecosystem
Hope this helps
I believe the answer is C.
The Sahel. The Sahel is a region of sub-Saharan Africa and it is also a zone of ecological transition between the Sahara to the north and the wetter savannas to the south. Sahel belt or Sahel is a tropical savanna ecoregion in Africa. Africa is the second largest continent. It has 54 sovereign countries.
Galileo preformed a famous experiment where he used a ball rolling on a ramp (inclined plane) to study the motion of objects under the influence of gravity. The ramp allowed him to make more precise measurements because the ball moved more slowly along the ramp than if it were simply dropped. Galileo discovered through this experiment that the objects fell with the same acceleration, proving his prediction true, while at the same time disproving Aristotle's theory of gravity (which states that objects fall at speed proportional to their mass). Galileo's conclusion from this thought experiment was that no force is needed to keep an object moving with constant velocity. Newton took this as his first law of motion. One result of the experiment surprised Galileo, and one surprises us. Galileo found that the heavy ball hit the ground first, but only by a little bit. Except for a small difference caused by air resistance, both balls reached nearly the same speed. And that surprised him.
According to history, Galileo’s experiment on falling bodies largely contributed to Isaac Newton’s Law of Gravity. In Galileo’s experiment, he is said to have dropped balls from the Leaning Tower of Pisa. The balls were made of the same material but had different masses. Galileo set out to prove that the time it took for these objects to reach the ground would be the same. Galileo proved that objects reached the ground at the same time,
