Use reasoning to lead to the answer of the following question:
He had said he would cook dinner, but first he needed to what?\nOptions:\n- hungry\n- buy a kitchen\n- buy food\n- buy groceries\n- eat food
 Reasoning process:
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Buying grocery is the first thing to be able to cook dinner. Dinner cant be cooked if you have npt bought grocery for it. Therefore, the final answer is buy groceries.
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