Which one of the following cannot be the unit of frequency of a sound

Which one of the following cannot be the unit of frequency of a sound wave ?

dB
s⁻¹
Hz
min⁻¹
This question was previously asked in
UPSC NDA-1 – 2021
Frequency is defined as the number of occurrences of a repeating event per unit of time. Its standard SI unit is Hertz (Hz), which is equivalent to inverse seconds (s⁻¹). Other units based on time inverse are also valid units for frequency, such as per minute (min⁻¹), per hour, etc.
A) dB (decibel) is a logarithmic unit used to measure the ratio of a physical quantity (usually power or intensity) to a reference value. It is commonly used to quantify sound intensity or loudness, not frequency.
B) s⁻¹ (per second) is the standard unit of frequency, equivalent to Hertz.
C) Hz (Hertz) is the standard SI unit for frequency.
D) min⁻¹ (per minute) represents cycles or events per minute, which is a valid unit for frequency (though not the SI unit).
Therefore, decibel (dB) cannot be a unit of frequency.
Frequency measures how often something happens per unit time (cycles/time). Decibel measures relative intensity or amplitude on a logarithmic scale.
The frequency of a sound wave determines its pitch. Higher frequency means higher pitch. The amplitude or intensity of a sound wave is related to its loudness, often measured in decibels.