Concept:In agriculture, soils are called
heavy or
light by how hard they are to work (plough, hoe, till), not by their weight. Clay soils are heavy soils; sandy soils are light soils.
Solution:Clay has very fine particles packed closely together, so it holds a lot of water and becomes sticky and plastic when wet.
When it dries it becomes hard and cracks.
Because of this, a hoe or plough needs much more effort (more draught power) to work clay soil, so it is called a heavy soil.
Sandy soil has large loose particles and is easy to work, so it is called a light soil, even though a bag of dry sand is not lighter than clay.
Stones (B) and large air spaces (C) describe gravelly and sandy soils, not heavy soils.
Key point: The stored key gave (A) high water holding capacity. That is a property of clay that helps make it hard to work, but the word
heavy itself means difficult to till.
Answer:Option D (are difficult to till)