Answer:
A. f/2.8
Explanation:
A hole within a lens, through which light travels into the camera body is referred to as the APERTURE.
It is typically expressed as "f number" in photography. Basically, a fast lens is any lens with a maximum aperture of f/4 or more i.e f/2.8 , f/1.8 , f/1.4 etc.
The smaller the number is the bigger the maximum aperture is. Hence, the bigger the maximum aperture the more light that your lens will allow in.
Therefore, the ideal aperture settings for a fast lens is f/2.8
