Which of the Following BEST Describes of the Object at the Center

Which of the following BEST describes of the object at the center of our galaxy?

A) 4 million $M_{\odot}$ in a volume the size of our solar system
B) 5 billion $M_{\odot}$ in a volume smaller then Jupiter's orbit
C) 20 $M_{\odot}$ in a volume the size of the Sun
D) several trillion $M_{\odot}$ in a volume 2 ly in diameter