Here are the answers to your questions: 4.10.1. The market structure depicted above is perfect competition. 4.10.2. The market price at which the business will sell his/her product is $\boxed{\text{50 rand}}$. 4.10.3. Opportunity cost is the value of the next best alternative that was foregone when a choice was made. It represents what must be given up to obtain something else. 4.10.4. It is not possible for a single business to adjust its selling price because, in perfect competition, individual firms are price takers. They are too small relative to the entire market to influence the market price and must accept the price determined by overall industry supply and demand. If they charge a higher price, they will sell nothing. 4.10.5. If businesses in a perfect market make an economic profit in the long run: • The existence of economic profits will attract new firms to enter the industry due to free entry. • This entry of new firms will increase the overall industry supply, shifting the industry supply curve to the right. • The increased supply will lead to a decrease in the market equilibrium price. • This process continues until economic profits are eliminated, and all firms in the industry earn only normal profit in the long run.