Dealing in quoted securities on the Nigerian Stock Exchange is restricted to aut...

The question is asking about who is allowed to trade in quoted securities on the Nigerian Stock Exchange. Quoted securities are stocks or bonds that are listed on a stock exchange, and can be bought and sold by investors. The question is asking who is authorized to trade in these securities.

The options include companies, brokers, investors, and principals. Out of these options, the correct answer is brokers. Brokers are individuals or firms that are authorized to buy and sell securities on behalf of investors. They act as intermediaries between buyers and sellers, and help to facilitate trades on the stock exchange.

Investors are individuals or institutions that buy and sell securities for their own accounts. Principals are individuals or firms that trade securities for their own account, rather than on behalf of others. Companies may also be involved in trading securities, but they are not specifically authorized to do so on the Nigerian Stock Exchange.

Therefore, the correct option for this question is B, brokers. To learn more about trading on the stock exchange, students can read about the roles of brokers and investors, as well as the process of buying and selling securities.