A wine sales rep that presents one wine at a time will have a hard time indeed.
A primary motivator for buyers (and human beings in general) is control. Control of a situation can only come from having choices, and having choices by definition means multiple options.
So on one hand your buyers are asking you to do the vetting process for them (“Find me some great wines”) but on the other hand don’t think that you have the final say. You need to offer choices, let them decide, and therefore let them feel ownership of the control.
Choice and control. Powerful ideas to keep in mind.