The cost of producing x ounces of gold from a new gold mine is C = f(x) dollars. (a) What is the meaning of the derivative f'(x)? What are its units? O f'(x) is the average production cost with respect to the number of ounces of gold produced. Its units are dollars per ounce. f'(x) is the total production cost. Its units are dollars. O f'(x) is the total amount of gold produced. Its units are ounces. O f'(x) is the rate of change of the production cost with respect to the number of ounces of gold produced. Its units are dollars per ounce. (b) What does the statement f'(800) = 18 mean? After 800 ounces of gold have been produced, the average production cost is $18/ounce. So the cost of producing 800 ounces is about $18/ounce. O After 18 ounces of gold have been produced, the average production cost is $800/ounce. So the cost of producing 18 ounces is about $800/ounce. After 800 ounces of gold have been produced, the rate at which the production cost is increasing is $18/ounce. So the cost of producing the 800th (or 801st) ounce is about $18. The total cost to produce 18 ounces of gold is approximately $800. (c) Do you think the values of f'(x) will increase or decrease in the short term? What about the long term? Explain. In the short term, the values of f'(x) will ---Select---because more efficient use is made of start-up costs as x increases. But eventually f'(x) might ---Select--- due to large-scale operations.