Substances that tend to stick together have a(n) ________ property.

• A. Cohesive
• B. Elastic
• C. Fluid
• D. Adhesive

Answer: (A)

Cohesion is the tendency of like molecules to attract and stick to each other, giving a substance the property of sticking together. This is why cohesive materials form clumps or hold together as a unit—water droplets stay intact because the water molecules attract one another, and clayey soil sticks together rather than crumbling apart. In earthmoving terms, cohesion helps explain how certain soils behave: cohesive soils have internal bonding that can give them strength and stickiness, which affects slope stability and compaction. The other ideas describe different behaviors—elastic is about returning to shape after deformation, fluid is about flowing, and adhesive is about sticking to other surfaces, not to itself.