Are the following statements true or false? If false, correct them. 

a. An investor who wishes to sell shares immediately should ask his or her broker to enter a limit order. 

b. The ask price is less than the bid price. 

c. An issue of additional shares of stock to the public by Microsoft would be called an IPO. 

d. An ECN (electronic communications network) is a computer link used by security dealers primarily to advertise prices at which they are willing to buy or sell shares.