The correct answer is: A. an object existence.
Intensity of sound is a physical quantity that describes the amount of energy carried by a sound wave per unit area. It is an objective quantity, meaning that it exists independently of any observer. The intensity of a sound wave can be measured using a sound level meter.
Option B is incorrect because the intensity of sound is not a subjective quantity. It is not something that is created by the mind or that depends on the individual’s perception.
Option C is incorrect because the intensity of sound does exist. It is a measurable quantity that can be objectively determined.
Option D is incorrect because the intensity of sound does not have both subjective and objective existence. It is an objective quantity that exists independently of any observer.