Wordpandit Question of the day

A cistern can be filled by two pipes filling separately in 12 min and 16 min respectively. Both pipes are opened together for a certain time but these are clogged. Because of this, only 7/8^th of full quantity water flows through the former and only 5/6^th through the latter pipe. The obstructions are suddenly removed and 3 minutes from that moment, the cistern is filled. How long was it before the full flow began?

a. 4.5 min
b. 2.5 min
c. 3.5 mn
d. 5.5 min

Solution to be posted later