The plum pudding model of the atom states that:

• A. Electrons are embedded within a diffuse, positively charged sphere, making the atom overall neutral.
• B. All of an atom's mass and positive charge are concentrated in the nucleus, and electrons exist in quantized energy levels.
• C. Electrons orbit a small, dense, positively charged nucleus in mostly empty space.
• D. Atoms are indivisible particles that cannot be broken down into smaller components.

Answer: (A)