Which icon represents that a referral is attached to an appointment?

The stethoscope with arrow icon symbolizes that a referral is associated with a specific appointment. This icon effectively communicates the connection between the appointment and the referral, allowing users to quickly identify that there are additional clinical considerations related to that visit. The combination of recognizable medical imagery with a directional element offers an intuitive way to signify that an action related to healthcare, such as referring a patient for further evaluation or treatment, is linked to the appointment.

In contrast, other icons serve different purposes; for example, the folder icon typically represents general file management or organization rather than specific medical references. The checkmark icon usually indicates completion or confirmation of an action but does not inherently convey that a referral is present. The paperclip icon is often used to denote documents or attachments but does not have the specific connotation of medical referrals associated with appointments like the stethoscope with arrow does. This makes the stethoscope with arrow the most appropriate choice for this scenario.