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