Two red and two overlapping balls in the center are surrounded by a green, fuzzy, circular cloud with a white line running through it. Two green balls sit on the white line, and a line leading a bracket around the balls is labeled A. A line leading to a bracket overlapping the white line is labeled B. Which is a characteristic of the part of the atom marked "A”?
It contains most of the mass.
It is negatively charged.
It is mostly empty space.
It is composed of electrons.