The correct answer is a business that specializes in trading stocks. This is because a brokerage firm is a type of financial institution that facilitates the buying and selling of stocks, bonds, and other securities on behalf of its clients. They act as intermediaries between buyers and sellers in the stock market, executing trades and providing investment advice. The other options listed in the question are not accurate definitions of a brokerage firm. The claims of ownership in a corporation refer to stocks themselves, not the firm that trades them. The collapse of the stock market in 1929 is a historical event related to the stock market, but not a definition of a brokerage firm. The market in which money is lent for periods less than a year refers to the money market, not a brokerage firm. Lastly, the practice of making high-risk investments with borrowed money is known as margin trading, which can be done through a brokerage firm but is not the definition of the firm itself.