Step 1: Define extensive properties.
Extensive properties are those properties of a system that depend on the amount of matter present in the system. Step 2: Analyze each option. (A) Specific heat: It does not depend on the quantity of substance, so it is an intensive property. (B) Volume: Volume increases with increase in the amount of substance, so it is an extensive property. (C) Density: Density remains constant regardless of the amount of substance, hence it is intensive. (D) Surface tension: It is independent of the amount of substance and is an intensive property. Step 3: Conclusion.
Volume is an extensive property because it depends on the quantity of matter present.