Explanation:
The correct option is 'a'. Inflammatory arthropathies (like rheumatoid arthritis) are classic contraindications for UKA because the disease affects the entire joint globally, inevitably leading to failure in the preserved compartments. An intact ACL is actually a prerequisite for a standard UKA.

Reference: Kozinn SC, Scott R. Unicondylar knee arthroplasty. J Bone Joint Surg Am. 1989;71(1):145-150.