Final answer:
The advertisement is most likely to state that if you buy the AC unit, they will install it, providing added value to the customer and enhancing the product's appeal.
Step-by-step explanation:
The advertisement for the AC unit most likely states that if you buy it, they will install it. This option provides a service incentive for the purchase, a common practice in the business to encourage customers to complete a transaction.
When companies sell products like AC units, they often offer installation services to stand out from competitors and to ensure that the product is set up correctly for optimal performance. This kind of service enhances customer satisfaction and can generate positive reviews and referrals, which are vital for a business's reputation and future sales.
In contrast, options suggesting that you do not buy it, or that installation is not provided, seem counterproductive and are, therefore, less likely to be used in an effective advertising campaign. Option 1, 'You buy it, we install it', is the most favorable and customer-friendly offering, corresponding with typical marketing strategies that leverage added value services to motivate a purchase.