the theory that government should not intefere in economic affairs is known as?

Question

A) popilism
B) supply-side economics
C) laissez-faire
D) capitalism

Here's what Populism is (assume that's what you meant):
http://en.wikipedia.org/wiki/Populism

Here's what supply-side economics is:
http://en.wikipedia.org/wiki/Supply_side_economics

Here's laissez-faire:
http://en.wikipedia.org/wiki/Laissez-faire

And here's capitalism:
http://en.wikipedia.org/wiki/Capitalism

I did read through and one of them does answer the question perfectly :)

Matt