Answer:
Software is a collection of instructions that tell a computer how to work. This is in contrast to hardware, from which the system is built and actually performs the work.
 
        
                    
             
        
        
        
printer is an output device because,
A printer is a device that accepts text and graphic output from a computer and transfers the information to paper, usually to standard size sheets of paper. 
So, a printer is an external hardware output device that takes the electronic data stored on a computer or other device and generates a hard copy of it.
therefore, it can be said that a printer is an output device
 
        
                    
             
        
        
        
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