A barrier has four inlets A, B, C and D. The barrier can be filled in 24 minutes through the first three inlets and it can be filled in 30 minutes through the second, the third and fourth inlet also it can be filled through the first and the fourth inlet in 40 minutes. How much time required to fill up the barrier by all the four inlets? A) 10 mins B) 15 mins C) 20 mins D) 25 mins E) None of the Above