The correct answer to the question is:
A. Because scientists had long supposed that most galaxies are like our own.
Explanation:
1. Scientists once thought that all galaxies had the same number of stars because they believed that most galaxies were similar to our Milky Way galaxy.
2. The assumption was based on the idea that galaxies shared certain characteristics, leading to the belief that they would have a similar number of stars.
3. This belief was later revised as scientists discovered a wide variety of galaxy types with different sizes, shapes, and compositions, each hosting varying numbers of stars.
4. The initial assumption was based on limited knowledge and understanding of the diversity present in the universe, which led to the misconception that all galaxies had the same number of stars.
