David works as a door-to-door salesperson for a company that manufactures electrical appliances. He has just met an elderly couple in their apartment. David is trying to sell an easy-to-use sandwich maker. He has spent 30 minutes explaining its benefits to his customers. He realized that the couple wants to buy the product. Which selling and customer service skill should David possess in order to close the sale? A. time management B. patience C. attentiveness D. persuasiveness
