Final answer:
Answer C, where a broker-dealer executes a customer's order on the NYSE, represents a secondary market transaction, as it involves the trading of shares between investors after the initial sale.
Step-by-step explanation:
The correct answer to the student's question regarding the secondary market transaction is C) A broker-dealer arranges for a customer's order to be executed on the NYSE. Initial Public Offerings (IPOs) and Additional Public Offerings (APOs) are examples of primary market transactions, where a company sells its shares directly to the public for the first time, or issues new additional shares, respectively. On the other hand, secondary market transactions involve the buying and selling of existing shares between investors after the initial sale by the company has occurred. The New York Stock Exchange (NYSE) is a venue where these transactions take place, meaning it provides liquidity by enabling investors to buy and sell shares from each other.