The band gap of germanium at room temperature is 

The correct option is 2

Concept:

The energy difference between the valence band and conduction band is called the forbidden energy gap.

Important Points

Bandgap Energy:

• The bandgap energy (Eg) in the minimum energy required to break a covalent bond and thus, generates an electron-hole pair
• The energy gap is the shortest distance between the valence layer and the conduction layer
• The Energy required for a photon to create an e-h pair is a little bit larger than band-gap in the case of indirect band-gap semiconductor