Which of the following expression is NOT correct for the \% excess air Select one: a. 100 (excess air)/(required air) b. 100(O2 entering the process O2 Theoretically required )/(O2 Theoretically required ) c. 100(O2 entering the process O2 Theoretically required )/(O2 entering the process) d. 100( excess O2)/(O2 entering the process - excess O2)