<prompt> An 18-yr-old boy was playing football when he suddenly twisted his knee on the ankle and he fell down. He got up after 10 minutes and again started playing, but the next day his knee was swollen and he could not move it. The most probable cause is -Medial meniscus tearAnterior cruciate ligament tearMedical collateral ligament injuryPosterior cruciate ligament injury  <response>: This boy has : -History of twisting injury to the kneeSwelling appearing next day.This is classical to the medial meniscal injury.In ACL injury swelling appears immediately due to hemarthrosis. 