<prompt> Most common cause of chronic retropharyngeal abscessInfective foreign bodyCaries teethCaries of cervical spineSuppuration of retropharyngeal lymph node  <response>: CHRONIC RETROPHARYNGEAL ABSCESS PREVEEBRAL ABSCESS AETIOLOGY :- It is tubercular in nature and is the result of i caries of cervical spine or ii tuberculous infection of retropharyngeal lymph nodes secondary to tuberculosis of deep cervical nodes. Ref:- Dhingra; pg num:-266,267 