The correct answer is D. Coal.
Graphite, diamond, and fullerenes are all allotropes of carbon, which means they are different forms of the same element. Coal is a mixture of organic compounds, including carbon, hydrogen, oxygen, and nitrogen. It is formed from the remains of plants and animals that have been buried and subjected to heat and pressure over millions of years.
Graphite is a soft, black mineral that is made up of carbon atoms arranged in a hexagonal lattice. It is a good conductor of electricity and heat, and it is used in a variety of applications, including pencils, lubricants, and electrodes.
Diamond is a hard, colorless mineral that is also made up of carbon atoms. It is the hardest natural substance on Earth, and it is used in jewelry and other applications where high hardness is required.
Fullerenes are a group of carbon allotropes that are composed of carbon atoms arranged in spherical, ellipsoidal, or tubular shapes. They were first discovered in 1985, and they have since been found to have a variety of interesting properties. Fullerenes are currently being studied for potential applications in a variety of fields, including medicine, materials science, and electronics.