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A student designed an investigation using composted materials. He put leaves in the first container, fruit and vegetable scraps in the second container, and a mixture of both in the third. After the materials decomposed, he grew plants in each of the three containers. What question was the boy investigating? (a) Which type of soil has the darkest color? (b)Which composted material makes the best soil? (c) What kind of soil needs the most water?
What is (B) Which composted material makes the best soil?