What would be the most logical initial action under these circumstances?

Check the results obtained with a leaner setting of the mixture.-gfdppm 2-19 (afh)in this case, engine roughness is probably caused by the mixture set too rich for the high altitude. when the carburetor heat is turned on, the warmer air entering the carburetor is less dense, and the mixture is further enriched. as a result, the engine roughness increases. the problem can usually be corrected by leaning the mixture. answer (b) is wrong because the pilot should first try the runup with a leaner mixture. answer (c) is not correct because detonation is the result of a mixture that is to lean.