All of the Following,except One,are Reasons Why the Stock Market

All of the following,except one,are reasons why the stock market is not a good example of a perfectly competitive market.Which is the exception?

A) The action of a single buyer or seller is able to affect the price of stocks.
B) You need to be rich in order to buy stocks.
C) There is not easy entry since a commission must be paid to a broker in order to trade.
D) Not all traders have equal access to information.