In database normalization, what problem does 4NF (Fourth Normal Form) address ?

Fourth Normal Form (4NF) is designed to eliminate redundancy caused by multi-valued dependencies. A relation is in 4NF if it is already in Boyce-Codd Normal Form (BCNF) and has no non-trivial multi-valued dependencies. A multi-valued dependency occurs when one attribute determines multiple independent values of another attribute, leading to data duplication. For example, if a course has multiple instructors and multiple textbooks independently, storing them in one table creates unnecessary combinations. By decomposing the table to separate these independent multi-valued facts, 4NF ensures data integrity and reduces anomalies. Partial dependencies (Option A) are addressed in Second Normal Form (2NF), while transitive dependencies (Option B) are handled in Third Normal Form (3NF). Join dependencies (Option D) relate to Fifth Normal Form (5NF), not 4NF. Therefore, the correct answer is Option C.