The Figure Given Below Shows the Demand [D and D']

The figure given below shows the demand [D and D'] and supply [S and S'] curves of shares of stock.Figure 17.2

-Why is it unlikely for even a very successful investor to continuously outperform the market?

A) Different investors have different risk appetites.
B) Individual investors have independent strategies.
C) The stock market is not subject to sufficient government regulations.
D) Investors often mimic the strategies of the successful investor.
E) The market is always inefficient.