Reverse Cold Chain is used for -
Carrying stool samples of polio patiens from a PHC to the lab
Transpoing outdated vaccines from PHC to district hospital
Transpoing vaccines to lab. to check its potency
Transpoing vaccine form camps to sub - centre
Ans. is 'a' i.e., Carrying stool samples of polio patients from MC to lab "Reverse cold chain" is for transpo of ble poliovirus in stool to an investigation centre.