calculation of total life of a tool

Question

The too life equation for HSS tool is VT^0.14f^0.7d^0.4 = Constant. The tool life (T) of 30 min is obtained using the following cutting conditions = 45 m/min, f=0.35 mm, d = 20mm. If speed (V), feed (f) and depth of cut (D) are increased individually by 25%, the tool life in min is

(a) 0.15                              (b) 1.06

(c) 22.50                            (d) 30.0