The hardness of 1000 litres of a water sample was removed by passing it through a zeolite softener which required 30litres of NaCl solution containing 1.5 gm/L NaCl for regeneration. The hardness of the water sample will b?

• A. 54.2 ppm
• B. 12.9 ppm
• C. 45 ppm
• D. 38.46 ppm