Use the band theory of semiconductors to choose the most correct statement below

a. A semiconductor primarily differs from an insulator in size of band gap.
b.Materials that are generally called conductors contain an overlap in the conduction and valence bands.
c. Conductors and semimetals are similar in band structure because of large band gaps.
d. Electrons in insulators at room temperature can easily cross the band gaps.
e. Semimetal materials are arranged structurally like metals but act as insulators because they have large band gaps.

a.
The size of the band gap is what defines a semiconductor and insulator. Insulators generally have gaps as large as several electron volts, usually preventing electrons from being excited into the conduction band at normal temperatures. Semiconductors have smaller band gaps, allowing electrons to be excited thermally and a small current to be established under an electric potential

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