Answer:
The problem with this classification is clastic sedimentary rocks are not formed with organic elements, that is, they do not form with the remains of organisms, such as shells, for example
Step-by-step explanation:
The student made an incorrect classification. This is because he classified a rock formed from shells as clastic sedimentary rock.
Shells are organic materials, as they are the remains of living organisms. Organic material is not capable of forming clastic sedimentary rocks, as these rocks are formed only by sediments. Remains of organisms, manage to form a type of rock called organic rock.