What is an efficient financial market?

What is an efficient financial market? 

An efficient financial market is one which has following features: 

(a) A market where asset pricing is such that none of the investor gets super normal returns in the long run. Pricing of assets tend to be fair. 

(b) The current price of an asset is an indicator of all information about that asset. 

(c) As per probability theorem, in an efficient market if A pick up a share in an expectation that it will do better, there are equal chances of its doing worse. 

(d) In such a market, risk adjusted expected returns on all assets will be equal. 

Hence, in an efficient financial market, one advises an investor to keep a diversified portfolio so that on an average, he is in a break-even situation. If one stock performs worse it is compensated by good performance of other.