From the given item, we are presented with four choices which are types of sedimentary rock. From the choices, we are to choose which among them is formed from a plant material over a long period of time. The answer to this item is letter coal. That is letter C.
Plants are the basis of a sedimentary rock, known as coal. Over the period of time, carbon is removed from the plants and combined with other organic materials. Generally, organic carbon in coal is 3%, and a major source of natural gas and oil.
