Operating System (OS) is the answer.
An application runs in/on an OS. It is not the OS itself. Like Word or Chrome are applications.
Systems is too generic and not specific enough to mean anything in this context. Throw away answer.
Network Operating System does not 'usually' run on a hard drive but on memory chips in things like routers, wireless access points and switches that move network traffic.
Answer:
the type of reference
Explanation:
There are many cell reference types eg relative,absolute and mixed cell referencing. if you write your cell reference in relative type then it will change as you copy it to another cell. if you select absolute cell referencing then it will not change if you copy to another cell.
Answer:
Credit Action .......I believe
The IMG tag is an image in an HTML page.
