This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood Bank & Transfusion Therapy, Subject name: Medicine
A patient is a known case of thalassemia major and is on repeated packed RBC transfusion. She is on iron chelators and has history of arrythmias. During the current BT, she has backache and looks very anxious. The next management is? 
Select and explain. 
A. Observe for change in colour of urine, B. Continuous BT and perform ECG, C. Stop BT and wait for patient to become normal and then resta BT, D. Stop BT and perform clerical check of blood group
D: Stop BT and perform clerical check of blood group
Answer: D: Stop BT and perform clerical check of blood group 
Explanation: Mismatched Blood Transfusion: Clerical ERROR is the most common cause