Commonest cause of lung abscess -: (A) Aspiration, (B) Hematogenous spread from distant site, (C) Direct contact, (D) Lymphatic spread
Answer is A. Routes of infection to lung

Aspiration of organisms that colonize the oropharynx (MC)
Inhalation of infections, aerosols
Hematogenous dissemination from an extrapulmonary site.
Direct inoculation (as in tracheal intubation or stab wounds)
Contiguous spread from an adjacent site of infection.