The correct answer is B. decibel.
A decibel (dB) is a logarithmic unit that expresses the ratio of a physical quantity (such as sound pressure, power, or intensity) to a reference value. The reference value is often chosen so that a change of 0 dB corresponds to a doubling of the physical quantity.
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.
Hertz (Hz) is the unit of frequency in the International System of Units (SI). It is defined as one cycle per second.
Joule (J) is the SI unit of energy. It is defined as the work done by a force of one newton acting over a distance of one meter.
Therefore, the correct answer is B. decibel.