Add Unique records in StudentCollection

Question

Hi

  I have below code & i want only distinct records in StudentCollection.

List<View_SessionDeliveryParticipant_Detailed_Report> objResult = bALSessionDeliveryParticipant.GetSessionDeliveryParticipantList(Convert.ToDateTime("2020-01-01"), Utility.CurrentDateTime(), MentorCollection, GroupCollection);
                if (objResult != null)
                {
                    foreach (var colum in objResult)
                    {
                        StudentCollection.Add(colum.StudentID.ToString());
                    }
                }

Thanks