The method used to remove temporary hardness of water is :
Correct option is B. Clark's method
Clark's method is used to remove the temporary hardness of water, in which bicarbonates of calcium and magnesium are reacted with slaked lime $$Ca(OH)_2$$.
$$Ca(HCO_3)_2+Ca(OH)_2\rightarrow 2CaCO_3\downarrow+2H_2O$$
$$Mg(HCO_3)_2+2Ca(OH)_2\rightarrow2CaCO_3\downarrow+Mg(OH)_2\downarrow+2H_2O$$
Hence, option B is correct.