Answer :
d) Open-end questions are the type of questions that allow salespeople to understand customer needs and expectations by encouraging them to respond freely.
Open-end questions enable salespeople to gain deep insights into customer needs by allowing for free-form responses, as opposed to limited-option closed-end questions. Unlike closed-ended questions, which offer respondents a limited set of options, open-ended questions provide the respondent with much freedom to express their thoughts in detail. This is crucial in sales as it provides insights into the customer's preferences, problems, and desires, informing better sales approaches and product development.