A has a comma then and so that isn't correct
B should be and I am
D should have an and in it
C is correct
* Main Electron a component- vacuum tube.
* Main memory- Magnetic drums and magnetic tapes.
* Programming language- Machine language.
* Power- Consume a lot of electricity and generate a lot of heat.
* were expensive to operate
Definition
URL a.k.a uniform resource locater, is simply the address of a World Wide Webpage.
Sentence example:
"Type a URL into a browser's address bar."
