Full-depth involute profile pinion with 20 teeth meshes with a gear that has 50 teeth for a module of 6mm?

Question

  What shall be the centre distance between the axes of pinion and gear when a 20⁰ full-depth involute profile pinion with 20 teeth meshes with a gear that has 50 teeth for a module of 6mm?                     

         (a) 70 mm                            (b) 140 mm

         (c) 210mm                           (d) 280 mm