Answer:
Sound intensity = The power of the sound wave per unit area
Step-by-step explanation:
Sound intensity is defined as the the power of the sound wave per unit area. Mathematically, it is given by :

P is the power
A is the area
It is also defined as the amount of energy flowing per unit time per unit area of cross section.
The SI unit of power is watts and the SI unit of area is m². So, the SI unit of sound intensity is W/m². Hence, the correct option is (C).