Assertion (A) : The resistivity of a semiconductor increases with temperature. Reason (R) : The atoms of semiconductors vibrate with larger amplitude at higher temperatures.

Both (A) and (R) are true and (R) is the correct explanation of (A).   Both (A) and (R) are true but(R) is NOT the correct explanation of (A).   (A) is true but (R) is false.   Both (A) and (R) are false.

Both (A) and (R) are false.

The resistivity of a semiconductor decreases with temperature. The covalent bonds of semiconductors break at higher temperatures.