Final answer:
The opportunity cost of the 10th unit of consumer goods when the economy is producing at production alternative C is 2 units of capital goods.
Step-by-step explanation:
The opportunity cost of the 10th unit of consumer goods when the economy is producing at production alternative C can be determined by examining the table given. It increases as more units of consumer goods are produced, indicating increasing opportunity cost. From the table, we can see that the opportunity cost of the 10th unit of consumer goods is 2 units of capital goods. Therefore, the correct answer is B.2 units of capital goods.