This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology and Rheumatology, Subject name: Medicine
Part of spine, involved in Rheumatoid arthritis is: 
Select and explain. 
A. Cervical, B. Thoracic, C. Lumbar, D. Sacral
A: Cervical
Answer: A: Cervical 
Explanation: Ans. is 'a' cervical spine (Ref. Harrison, 17/e p 2086 & 16/e, p 1971 (15/e, p 1932)).Rheumatoid arthritis commonly involves joints of hands, wrist, knees, elbow, ankle, feet in symmetrical* manner."The axial skeleton involvement is usually limited to upper cervical spine" - Harrison, 15/e, p. 1932.