Concept:Organically formed sedimentary rocks come from the remains of plants or animals.Explanation:Coal is a classic example because it forms from ancient plant remains buried and compressed over millions of years.Granite is an igneous rock formed from cooled magma.Rock salt is a chemical sedimentary rock formed by evaporation of saline water.Sandstone is a clastic sedimentary rock made from cemented sand grains.Since the question asks for an organically formed sedimentary rock, coal matches the definition exactly.Answer:A. coal