What are "the fundamental categories of economics"? I had an introductory class in marketing last week, and the professor wanted to test our previous knowledge of economics (we are juniors). 
He asked us this simple question: "What are the fundamental/basic categories in economics?"

Confused by the vagueness of the question, most of us said labor, capital, profit, markets... All sorts of things, but none were apparently correct. In the end, he said that the correct answer is: 


cost
result (as in profit or revenue)
time


He continued to say that we define everything in economics on the basis of these three categories.

My questions now are: is this true? Do I really have such a significant knowledge gap that I somehow missed this crucial piece? Where can I find the confirmation of his statement?

If this is not true, can you please refer me to where I can find the answer to this question?

Thanks
Cost covers all the inputs you mentioned and markets don't need to exist. Rent seeking is a perfectly valid alternatives to markets. So having to choose (cost/spend) between different alternatives (profit) is all there is. You can even include time as a cost and reduce it to two factors.