Acetylcholine on respiratory tract acts by all except?

Ans. is 'd' i.e., Inhibits chemoreceptor of carotid bodyActually both option c & d are incorrect as carotid body chemoreceptors are not found in respiratory tract. Carotid body and aoic odies are located in connective tissue associated with wall of common carotid aery and arch of aoa, respectively.But, option 'C' can be considered correct as acetylcholine stimulates chemoreceptors (not inhibits)."Acetylcholine increases chemoreceptor discharge in carotid body". - Principles of medical physiologyThus best answer here is option 'd'.About option a & b Acetylcholine causes bronchoconstriction and increases tracheobronchial secretions.