Carbon mono-oxide (CO) is released in reaction catalyzed by-

Heme Oxygenase (EC no- 1) catalyzes degradation of Heme by oxygenation and releasing CO in the reaction (see fig). With regard to other options which are as follows: Decarboxylases(Option a) - produce CO2 Elimination reactions. Carboxylases(Option b) - use CO2 as a Substrate. Pyruvate Dehydrogenase(Option d) - used to conve Pyruvate into Acetyl CoA formed in mitochondria.