A 14yr old male complains of low grade fever, palpitations that did not show any improvement on rest, dysopnea on exertion and joint pains involving multiple major joints.He has h/o soar throat 3 eeks prior to these symptoms.On examination his bp is 100/70mmhg, PR 88/min, RR 16/min,have pedal edema and others were negative.On CVS examination pan systolic murmur is heard.What's the probable diagnosis? a. INFECTIVE ENDOCARDITIS b. RHEUMATIC FEVER c. ISCHAEMIC HEART DISEASE d. RHEUMATOID ARTHRITIS