STATEMENT-1: If the accelerating potential in an X-ray tube is increased, the wavelengths of the characteristic X-rays do not change.
because
STATEMENT-2: When an electron beam strikes the target in an X-ray tube, part of the kinetic energy is converted into X-ray energy.
Official answer: B
Statement 1. Characteristic lines come from transitions between the target atom's inner levels, fixed by the target material; raising the voltage only increases their intensity (and shortens the continuous cut-off). True.
Statement 2. Part of the electrons' kinetic energy becomes X-rays (most becomes heat). True, but it does not explain why the characteristic wavelengths are fixed.
(B)