Agricultural economist: Over the past several years, increases in worldwide grain production have virtually ceased. Further increases will be extremely difficult; most usable farmland is already being farmed with near-maximal efficiency. But worldwide demand for grain has been increasing steadily, due largely to continuing population growth. Hence, a severe worldwide grain shortage is likely. Which one of the following most accurately describes the role played in the agricultural economist's argument by the claim that further increases in worldwide grain production will be extremely difficult? ['It is a description of a phenomenon, a causal explanation of which is the main conclusion of the argument.', 'It is one of the two conclusions drawn by the agricultural economist, neither of which is used to provide support for the other.', "It is a prediction for which the agricultural economist's first claim is offered as the primary justification.", "It is an intermediate conclusion that is presented as evidence for the argument's main conclusion."]