In a mine site, the cost of shaft sinking in lakhs of rupees is given as 2.64D + 34.8, where D is the shaft depth in m. In the same site, the corresponding cost of driving an incline is 0.96 L, where L is the length of the incline in m. Assuming L by D ratio is 3.0, the depth in m beyond which the shaft sinking becomes more economical is

A. 43

B. 48

C. 145

D. 155

Answer: Option C