Ans. is 'c' i.e., Polymerase chain reactionRef: Harrison, 17th/e, p. 1074,19th/e, p. 1165 and Ananthanarayan, 9th/e, p. 415Amplification assays such as ligase chain reaction and polymerase chain reaction are the most sensitive chlamydial diagnostic method.Other methods are:(a) Cell culture: Sensitivity (60-80%).(b) Direct immunofluorescent antibody test: Sensitivity 70-80% and quite specific.(c) ELISA: 60-80%.