Answer: (D) (4/3) hour
Explanation: Time taken by A alone = x hours (suppose)
Hence, Time taken by A + B + C = (x – 6) hours
Time taken by B alone = (x – 5) hours
Time taken by C alone = 2(x – 6) hours
Now, 1/(x – 6) = 1/x + 1/(x – 5) + 1/2(x – 6)
Hence x = 4/3