​Which of the following can increase customer interest?

A) ​Advertising
B) Promotional activities
C) Service
D) ​All of the above

All of the above options can increase customer interest. Advertising can create awareness and showcase the features and benefits of the product or service to potential customers. Promotional activities such as discounts, free trials, or giveaways can incentivize customers to try the product or service. Providing excellent service can create positive word-of-mouth and repeat business. Therefore, using these strategies together can lead to greater customer interest and ultimately, more sales.