Ans. is 'a' i.e., Juvenile rheumatoid ahritis Causes of knee pain in adolescence (..)Time of the knee pain helps in the diagnosis of the disorders : - I. Night pain indicates i) Inflammatory disorder ---)Juvenile rheumatoid ahritis. ii) Bursitis, synovitis iii) Tumor Osteosarcoma Pain at the end of the day and after activity indicates i) Mechanical pain due to injury Continuous pain present day and night indicates i) Infection ---> Osteomyelitis, Septic ahritis ii) Idiopathic adolescent anterior knee pain syndrome (Chondromalacia patella).