Concept:The water a soil holds adds to its weight. The soil with the highest water-holding capacity gains the most weight per unit amount.Explanation:Clay particles are the finest, so clayey soil has very small pore spaces and a very large surface area that hold water tightly.Loamy soil holds a moderate amount, sandy soil little, and gravel almost none, because their large particles leave large pores through which water drains away.Answer:Option B (clayey soil)