S1: The heart is pump of life.nP : They have even succeeded in heart transplants.nQ : Nowadays surgeons are able to stop a patients heart and carry out complicated operations.nR : A few years ago it was impossible to operate on a patient whose heart was not working properly.nS : If heart stops we die in about five minutes.nS6: All this was made possible by the invention of heart-lung machine.nThe Proper sequence should be:

• A. SRQP
• B. SPRQ
• C. SQPR
• D. SRPQ