Final answer:
Physical properties are characteristics of a substance that can be observed or measured without changing its identity.
Step-by-step explanation:
A physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance. Examples of physical properties include color, density, hardness, and melting and boiling points. These properties can be observed or measured without causing any chemical changes to the substance. Therefore, the correct answer to your question is b) Physical properties.