What is the approximate diameter of the Milky Way galaxy?

The diameter of the Milky Way galaxy is estimated to be approximately 100,000 light-years. This measurement is based on various observational techniques, including mapping the distribution of stars, gas, and dust within the galaxy, as well as measurements of the galaxy's rotational dynamics.

The 100,000 light-year diameter provides a reasonable context for understanding the size of our home galaxy in relation to the vast universe. It indicates that the Milky Way is a large spiral galaxy, containing hundreds of billions of stars, along with planetary systems, dark matter, and interstellar material.

The larger numbers provided in the other options, such as 10 million, 2.5 million, and 50 million light-years, greatly exceed the actual size of the Milky Way. These figures may be more representative of the distances to other galaxies or structures within the universe rather than the physical dimensions of our own galaxy. Thus, the choice of 100,000 light-years aligns accurately with the astronomical consensus on the Milky Way's size.