Which of the Following Pieces of Evidence Best Supports Bohr's

Which of the following pieces of evidence best supports Bohr's idea that electrons occupy specific energy levels within an atom?

A) Sodium atoms become positive ions when they lose electrons.
B) Each element emits a unique brightline spectrum when it falls from an excited state to a ground state.
C) Beryllium atoms bombarded with alpha particles produce beams that are not influenced by magnetic fields.
D) Each element has physical and chemical properties that are unique to that element and different from those of other elements.