Which of the following is a sign that customers are having trouble using a particular device to make purchases?

The correct answer is "Analytics shows you have a lot of mobile visitors, but very few purchases through mobile." This indicates a clear disparity between mobile engagement and conversion, suggesting a potential usability issue on mobile devices that prevents visitors from completing purchases. For example, a website might not be mobile-responsive, making navigation and checkout difficult on smaller screens. "A specific product is not selling much compared to your other products" suggests an issue with the product itself, its pricing, or marketing, not necessarily a device-specific usability problem across the entire site. "You get a lot of questions about your return policy" points to a lack of clarity in your policy or customer concerns about returns, not a technical barrier related to device usage during the purchase process.