<prompt> CAP in Lac operon is an example ofPositive regulatorNegative regulatorConstitutive expressionAttenuation  <response>: Catabolite activator proteinCAP must bind to cAMP to activate transcription of the lac operon by RNA polymerase. CAP is a transcriptional activator with a ligand-binding domain at the N-terminus and a DNA-binding domain at the C-terminus. 