Which of the following best defines the Milky Way galaxy?

The Milky Way galaxy is defined as a vast collection of stars, gas, dust, and dark matter, organized into a spiral structure. The key aspect of the Milky Way is that it includes our Solar System, which consists of the Sun and the planets, including Earth, that orbit it. This makes option D the best choice, as it directly states a specific and accurate relationship between our Solar System and the Milky Way galaxy.

While the other options touch upon celestial bodies, they do not accurately capture the scale or structure of the Milky Way. For instance, describing it as a large planet or a collection of a few hundred stars does not reflect its true nature, which includes hundreds of billions of stars and potentially as many planets. Similarly, while the Milky Way does contain multiple solar systems, this description does not encompass the full scope or significance of our galaxy, particularly in relation to our own Solar System's placement within it. Thus, acknowledging that the Milky Way includes our Solar System highlights its importance in understanding our galaxy's vastness and structure.