3 Why should you use the lowest
ISO possible?
A so as to use a faster shutter speed
B so as to use a smaller aperture
C To ensure that pictures are full of
detail and color

it is c i believe

Explanation: When you have enough light for a good exposure with your chosen aperture and/or shutter speed – you should choose the lowest ISO value. This makes the camera’s sensor the least sensitive to light it can be. The benefit of this is the lack of grain or noise in the final image.

pitch- the definition of pitch is as follows:

"the quality of a sound governed by the rate of vibrations producing it; the degree of highness or lowness of a tone."