MC site of TB reactivation in lung is?

Ans. (a) ApexPostprimary (Adult-Type) DiseaseAlso referred to as reactivation or secondary TB, postprimary TB is probably most accurately termed adult-type TB, since it may result from endogenous reactivation of distant latent infection or recent infection (primary infection or reinfection).It is usually localized to the apical and posterior segments of the upper lobes, where the substantially higher mean oxygen tension (compared with that in the lower zones) favors mycobacterial growth