Which of the following statements is true? a) Neither chemical nor physical changes involve a change in appearance. b) Both chemical and physical changes can involve a change in appearance. c) Only physical changes involve a change in appearance. d) Only chemical changes involve a change in appearance.

The answer to your question is B. Both chemical and physical changes can involve a change in appearance.
Physical changes do not change the molecules in a substance, only the way the substance looks. A great example showing a physical change is water. Water, at room temperature, is a liquid. If the temperature of the room is lowered to 0℃, the water will freeze and become a solid. The water will now look different but the water molecules are still the same. Now if we take that frozen water and heat it to 100℃, the water will turn into a gas. The water no longer looks frozen, but its molecules are the same.
A chemical change does change the molecules in a substance, basically meaning, you no longer have the same substance you began with. There are five main ways to tell if a chemical change occurred.
1) Color Changes2) Precipitate Forms 3) Temperature Change 4) Gas Production 5) Light Emission
There are many examples of a change of appearance in a chemical change. If you cook an egg, the egg is undergoing a chemical change and the egg looks very different once you have finished cooking. In this example there was a color and temperature change. Another example is the burning of wood. The wood looks different from before and after the burning and the molecules of the wood are different. The chemical change was noted by temperature, color and light emission.

Although it might not seem as obvious as physical changes, a chemical reaction or transformation can also involve a change in appearance. For example, when a blacksmith heats a piece of steel bar at 2500° F, the steel bar will change in appearance in two ways: its color will turn orange-red, and its edges will become more dull. These transformations in appearance are due to a chemical change caused by extreme temperatures.
Another common example of a chemical change is the formation of bubbles, which is caused by different levels of gas molecules in water. Leaving a glass of flat water in a warm room will lead to the formation of tiny bubbles, thus changing its appearance.
Physical changes will definitely change the appearance of matter. The most common example of both physical and chemical changes is the transformation of water into ice, or water into vapor.
https://extension.tennessee.edu/publications/Documents/W401.pdf