Arrange the following in the increasing order of their energy band ga…

The correct answer is Option (2) → (D), (B), (A), (C)

These are the group-IV elements. Going down the group the energy band gap falls, from an insulator (carbon in the form of diamond) to a semiconductor (silicon, germanium) to a metal-like element (tin). The approximate gaps are

C (diamond): 5.4 eV
Si: 1.1 eV
Ge: 0.67 eV
Sn: about 0 eV (0.08 eV for grey tin)

Arranging them in increasing order of the gap:

    \( \displaystyle \mathrm{Sn} \lt \mathrm{Ge} \lt \mathrm{Si} \lt \mathrm{C} \)

that is (D), (B), (A), (C).

NCERT (2026-27):
Extrinsic Semiconductor – “… The difference in the resistivity of C, Si and Ge depends upon the energy gap between their conduction and valence bands. For C (diamond), Si and Ge, the energy gaps are 5.4 eV, 1.1 eV and 0.7 eV, respectively. Sn also is a group IV element but it is a metal because the energy gap in its case is 0 eV.”