Where is donor energy level located ?

The correct answer is Option (2) → In n type semiconductor just below conduction band

A donor is a pentavalent impurity (such as P, As or Sb) added to silicon or germanium. Four of its five valence electrons form bonds; the fifth is held so weakly that very little energy frees it. Its energy level, the donor level, therefore lies just below the bottom of the conduction band, and doping with donors gives an n-type semiconductor.

NCERT (2026-27):
Extrinsic Semiconductor – “… In the case of extrinsic semiconductors, additional energy states due to donor impurities (E_D) and acceptor impurities (E_A) also exist. In the energy band diagram of n-type Si semiconductor, the donor energy level E_D is slightly below the bottom E_C of the conduction band and electrons from this level move into the conduction band with very small supply of energy.”