The correct answer is: a) Natural mineral pigments.
Natural mineral pigments are the most common type of pigment used in monastery murals. They are derived from minerals such as ochre, umber, and lead white. These pigments are very stable and can last for centuries. They are also very versatile and can be used to create a wide range of colors.
Synthetic dyes are another type of pigment that is sometimes used in monastery murals. However, they are not as common as natural mineral pigments. Synthetic dyes are derived from organic materials such as plants and animals. They are not as stable as natural mineral pigments and can fade over time.
Crushed flower petals are not a common type of pigment used in monastery murals. They are not as stable as natural mineral pigments or synthetic dyes and can fade over time. They are also not as versatile as natural mineral pigments and can only be used to create a limited range of colors.
Charcoal and soot are not pigments at all. They are blackened materials that are created by the incomplete combustion of organic materials. They are not used in monastery murals because they are not stable and can fade over time.