S<sub>1</sub>: The mail is first collected from different letter boxes.<br>P: From there it is sent to the head post office.<br>Q: It is then sorted out at the sorting office.<br>R: The mail is again sorted out at the head office by the concerned beat postman.<br>S: The sorted mail is sent to the zonal post office.<br>S<sub>6</sub>: Finally it is delivered to us.<br><br>The Proper sequence should be:

Correct Answer: QPRS
It is then sorted out at the sorting office. From there it is sent to the head post office. The mail is again sorted out at the head office by the concerned beat postman. The sorted mail is sent to the zonal post office.