The fixed cost for a steam line per meter of pipe is $500X+$50 per year. The cost for loos of heat from the pipe per meter is $5.2/X^0.5 per year. X is a continues dosing variable and represents the thickness of insulation in meter. The optimal thickness of the insulation is? Select one: a. 0.0305 meters b. 0.0205 meters c. 0.0301 meters d. 0.0600 meters