Which of the following is the correct match?

• A
  Ordinary form of borax $:$ $Na_2B_4O_7 \cdot 5H_2O$
• B
  Colemanite $:$ $Ca_2B_6O_{11} \cdot 5H_2O$
• C
  Boronatrocalcite $:$ $2Mg_3B_8O_{15} \cdot MgCl_2$
• D
  Octahedral form of borax $:$ $Na_2B_4O_7 \cdot 10H_2O$