Acceptor level lies close the valence band
The acceptor level is a level within the band gap of a semiconductor that is created by doping the semiconductor with an impurity atom that has fewer valence electrons than the atoms in the host material. This creates a localized energy level within the band gap that is closer to the valence band. Electrons from the valence band can easily transition to this level, creating a hole in the valence band.

Donor level lies close to the valence band
The donor level is a level within the band gap of a semiconductor that is created by doping the semiconductor with an impurity atom that has more valence electrons than the atoms in the host material. This creates a localized energy level within the band gap that is closer to the valence band. Electrons from this level can easily transition to the valence band, creating an excess of electrons.

n type semiconductor behaves as an insulator at 0 K
An n-type semiconductor is a semiconductor that has been doped with impurity atoms that donate extra electrons to the material. These extra electrons occupy the conduction band, making the material conductive. However, at 0 K (absolute zero temperature), the electrons in the conduction band have very low energy and are unable to move freely. As a result, the n-type semiconductor behaves as an insulator at 0 K.

p type semiconductor behaves as an insulator at 0 K
A p-type semiconductor is a semiconductor that has been doped with impurity atoms that accept electrons from the material, creating holes in the valence band. These holes can move through the material, making it conductive. However, at 0 K, the holes in the valence band have very low energy and are unable to move freely. As a result, the p-type semiconductor behaves as an insulator at 0 K.

Explanation of correct answer (option C)
The correct answer is option C, which states that statement 1 (Acceptor level lies close to the valence band) and statement 4 (p-type semiconductor behaves as an insulator at 0 K) are correct.

Statement 1 is correct because acceptor levels are created by doping the semiconductor with impurity atoms that have fewer valence electrons. These levels are located within the band gap and are closer to the valence band. Electrons from the valence band can easily transition to these levels, creating holes in the valence band.

Statement 4 is correct because at 0 K, the energy of the holes in the valence band of a p-type semiconductor is very low. As a result, these holes are unable to move freely through the material, making the p-type semiconductor behave as an insulator at 0 K.

Therefore, option C is the correct answer as it correctly identifies the two statements that are true.