A colony of 50 people is served by a septic tank. The rate of water supply is 90lped in the colony and 40% of it is going to the septic tank. The retention period of the tank is 24 hours. The length of the septic tank is _____ meter (rounded off to two decimal places).

• A. 34.2
• B. 3.42
• C. 342
• D. 0.342