Final answer:
Sagittarius A* is approximately 4 million times the mass of the Sun, making the correct answer d. 1,000,000. This massive black hole has a profound effect on the Milky Way Galaxy's structure and dynamics.
Step-by-step explanation:
Sagittarius A* (Sgr A*) is a massive object located at the center of our Milky Way Galaxy. It has been determined by astronomical observations that Sgr A* is approximately 4 million times the mass of our Sun. When comparing Sgr A* to our neighboring star, the correct answer to the student's question is d. 1,000,000. This means that Sgr A* is about 4 million solar masses, which signifies not only its immense mass but also its significant impact on the surrounding space, including the orbits of nearby stars. This information is critical in understanding the dynamics of our galaxy and also in calculating properties such as the Schwarzschild radius of the black hole, which is related to the mass of the object and determines the size of the event horizon.