Final answer:
The best course of action is to apologize for the inaccurate ad, pay for a professional installation, and remove the incorrect advertisement to avoid further confusion and maintain customer satisfaction.
Step-by-step explanation:
In this situation, the advertisement has created an expectation for the customer which the store is not ready to fulfill due to a discrepancy in services offered. The ethical and customer-friendly solution would be option D) Apologize for the inaccurate ad, pay for a professional to install the AC unit, and take down the inaccurate ad to prevent further confusion. This way, the company honors the commitment it implied through the ad and corrects the error to maintain customer trust and satisfaction. It's important to address and rectify such situations transparently and efficiently.