Final answer:
AraC acts as an activator control protein that promotes transcription in the presence of arabinose in the regulation of the ara operon.
Step-by-step explanation:
AraC, in the context of the ara operon, acts as an activator control protein that promotes transcription in the presence of the sugar arabinose. When arabinose binds to AraC, the complex binds to the initiator site and enhances the binding ability of RNA polymerase to the promoter, resulting in the induction of transcription. Therefore, the true statement about AraC's regulation of the ara operon is that it acts as an activator control protein that promotes transcription in the presence of arabinose.