Final answer:
The statement is false. Comparative advantage is determined by lower opportunity cost, not just lower cost in absolute terms. A farmer has a comparative advantage in wheat if the opportunity cost of producing wheat is lower than that of any other crop.
Step-by-step explanation:
The statement that a farmer has a comparative advantage at growing wheat if his cost of growing wheat is smaller than his cost of growing any other crop is False. Comparative advantage is about producing a good at a lower opportunity cost than that of another producer, which means a farmer could have a higher actual cost of growing wheat but if the opportunity cost (what they give up by not producing the next best alternative) is lower in wheat than in any other crop, then they would still have a comparative advantage in growing wheat.
For example, even if a farmer faces fierce competition in the wheat market and finds it hard to make money, it might still be the case that wheat is their best option if producing other crops would entail giving up even more in potential earnings. In such a scenario, even if the cost of growing wheat is not the smallest, they would still have a comparative advantage in wheat production. Farmers might switch crops not based solely on cost but on the potential earnings and opportunity cost associated with each possible crop.