Which of the Following Is/are Correct Postulates of Bohr's Theory

Multiple Choice

Which of the following is/are correct postulates of Bohr's theory of the hydrogen atom ?
1.The energy of an electron in an atom is quantized (i.e. only specific energy values are possible) .
2.The principal quantum number (n) , specifies each unique energy level.
3.An electron transition from a lower energy level to a higher energy level results in an emission of a photon of light.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1, 2, and 3