Randy is building a house. he wants to put stucco on the outside walls of his house. to make stucco, he needs sand. he lives on the beach, so he decides to use the soil in his backyard. before he can use the sand, he must remove the other substances from the soil. he separates the larger pebbles and other debris from the finer sand by sifting it with wire mesh. randy mixes the sand with concrete and water to make the stucco he needs. which sentence provides the best evidence that randy's backyard soil is a heterogeneous mixture?
(a)-before he can use the soil, he must remove the substances other than sand in the soil.
(b)-to make stucco, he needs sand.
(c)-he separates the larger pebbles and other debris from the finer sand by sifting it with wire mesh.
(d)-randy mixes the sand with concrete and water to make the stucco he needs.