Correct : c

I: Logical schema → N: Relations
The logical schema describes the overall structure of the database in terms of relations (tables), attributes, constraints and their relationships. It is what the DBA sees and works with. Relations belong to the logical level.
II: Physical schema → M: File organization and indexes
The physical schema describes how data is actually stored on disk — file organization, indexing structures, access paths, storage details. This is the lowest level dealing with physical storage.
III: External schema → L: Views
The external schema (also called user views or subschema) defines how different users or applications see the data. Each user gets a customized view — hiding parts of the logical schema they don''t need. Views belong to the external level.
So the correct mapping is I-N, II-M, III-L → Option C.