Of the options presented in this problem, the answer would be C. reactivity.
Physical property is commonly known to be a s observable property of matters. This means, as the name suggests, that the physical property can be observed without the use of special instrument and other things to observe. Another thing is that it can be measured and put on a value and a standard unit of measurement. The physical property helps a lot in differentiating matter to matter and also aids in determining their uses and hazards as well. The boiling point and freezing point go hand in hand as to they are opposite to each other and are observed by the application of heat and the application of cold environment, respectively. As for density, it can be observed with the object being in contact with an adequate amount of water, if it will sink, float, or stay in the middle.
