Final answer:
The transaction cost of buying and selling a stock includes broker's commissions, dealer's bid-asked spread, and price concessions due to illiquidity.
Step-by-step explanation:
The (transaction) cost of buying and selling a stock includes:
Broker's commissions
Dealer's bid-asked spread
Price concessions that investors may be forced to make when investors need to sell a large amount of stocks quickly (i.e., so-called "price impact" due to illiquidity)
The correct answer is d.I, II, and III. All three options contribute to the transaction cost of buying and selling a stock.