<prompt> TRUE regarding presentation of primary T.B isBilateral pleural effusion with negative Tuberculin testUnilateral hilar lymphadenopathySustained chronic pyrexiaBilateral pleural effusion with postive Tuberculin test  <response>: Because most inspired air is distributed to the middle and lower lung zones, these areas are most commonly involved in primary TB. The lesion forming after initial infection Ghon focus is usually peripheral and accompanied by transient hilar or paratracheal lymphadenopathy, which may or may not be visible on standard chest radiography. Ref Harrison 19th edition pg 1108 