Ans. is 'a' i.e. Anti-ccp antibody Rheumatoid factor is an autoantibody, usually IgM directed against the Fc region of IgG.Despite its name, rheumatoid factor is not specific for rheumatoid arthritis, it can also be seen in wide range of autoimmune disorders, inflammatory disease and chronic infections. *Anticitrullinated peptide antibody test (Anti ccp) test is more specific than rheumatoid factor for diagnosis of rheumatoid arthritis, It may be positive very early in the course of the disease.Oxford Journal of medicine states "Anti-cyclic citrullinate peptide (anti-ccp) antibody testing is particularly useful in the diagnosis of rheumatoid arthritis with high specificity, present early in the disease process and has ability to identify patients who are likely to have severe disease and irreversible damage. Anti ccp antibodies have not been found at a significant frequency in other diseases to date and are more specific than Rheumatoid factor for detecting rheumatoid arthritisAlso knowDiagnosis of Rheumatoid arthritisThere is no single sign, symptom or test result that allows the definitive diagnosis of rheumatoid arthritis.Instead, the diagnosis is based on a consideration of many factors, including the presence of characteristic signs and symptoms of rheumatoid arthritis, the results of laboratory tests, and the result of X-rays.The diagnosis of R. A. is based on the presence of at least four of the following criteria :Morning stiffness that lasts at least one hour and that has been present for at least six weeks.Swelling of at least three or more joints for 6 weeks.Swelling of the wrist, metacarpophalangeal (MCP), or proximal interphalangeal (I.T.P.) joints for at least six weeks.Swelling of the same joint on both sides of the bodyChanges in hand X-rays that are characteristic of rheumatoid arthritisRheumatoid nodules of the skin.Rheumatoid factor found in the blood.