Questions

A piano is a musical instrument which has keys, pedals and strings in which the strings are struck by hammers.

Answer:  K

Explanation:  In each row, the product of the left and right hand numbers equals the sum of the numerical values of the three letters.

Operating system software is that manages resources on a network.

Epiglottis is that prevents food from entering the windpipe. 

It is a cartilageous flap that flaps opens and closes when swallowing. When you swallow, the epiglottis flattens backward to cover the entrance to your larynx and prevent food from entering the lungs and windpipe. The epiglottis returns to its usual position after swallowing.