Final answer:
The Schwarzschild radius of the Milky Way as a black hole would be less than a tenth of a light year, significantly smaller than the 13,000 light-years distance from Earth to the galaxy's center.
Step-by-step explanation:
The Schwarzschild radius (Rs) of a black hole is given by the formula Rs = 2GM/c², where G is the gravitational constant, M is the mass of the object, and c is the speed of light. The mass of our Milky Way galaxy is about 8.0 × 10¹¹ solar masses. Using the above formula with these values, we find that the Schwarzschild radius of the Milky Way, if it collapsed into a black hole, would be approximately 1×10¹² kilometers, which is about a tenth of a light year.
Comparing this to our distance from the center of the Milky Way, which is about 13,000 light years, the Schwarzschild radius is significantly smaller. Therefore, the correct answer to the size of the Schwarzschild radius, in light years, if our Milky Way galaxy collapsed into a black hole is less than a tenth of a light year, which is not one of the options provided, indicating a possible issue with the question or the provided choices.