Option C: R(A, B, C, D) and the Functional Dependency set = {AB→C, C→AD}
Candidate keys are AB, CB & C→ AD violates BCNF, so decompose it using BCNF decomposition algorithm (Source: Navathe). C+ = CAD. Decomposition is R1(BC) and R2(CAD).
C→AD is preserved but AB → C can’t be preserved. So decomposition is in BCNF but not dependency preserving hence option C is the right answer.