The answer is The unsorted sand and rock is the least porous. The porousness of a solid material is dependent on the size of holes within it. This can be tested by how quickly, the material can pass a liquid through it. The bigger the holes, the higher the porousness, In this case, the unsorted sand and rock have the smallest holes between its particles.
<span>It is asked in this problem to determine which of the combination of materials is the least porous among all. Porosity is the ratio of the volume of pores or voids present per volume of the total mixture. Loosely packed gravel translaes to porous property already while big rocks can also employ large gaps in between. answer then is B. </span>
