which what

[Unregistered]

What is the difference between what and which and who?

Which is correct?

Which is the largest country in the world?
What is the largest country in the world?

question:What / Which colour trousers would you like?
answer: I like the green one. I like green

What / which football team do you support?

Which actor do you like ?
What actor do you like?

 

[oregeezer]

"Which" implies a choice, "what" asks for an answer from the universe of things 'we are talking about'.