Scientist are always learning new things. which of the following shows how scientist use observations to gain new understanding about the world?
A. scientists have discovered new planets orbiting a star by detecting a wobble in the star's motions.
B. Scientists hope to learn more about how many stars are in space.
C. Scientists are familiar with some galaxies, but they do not know how many galaxies exist.
D. Scientist wonder if other plants can support life, and some scientist wonder if there are aliens.