Answer
A. structure
Step-by-step explanation
Physical properties can be observed or measured without changing the composition of matter. Physical properties are used to observe and describe matter.
Physical properties include appearance, texture, color, odor, melting point, boiling point, density, solubility, polarity, and many others.
Therefore, the physical properties of materials are determined by their chemical composition and their internal structure, like grain size or crystal structure.
So the correct answer is option A. structure.