The reaction of ${\mathrm{H}}_3{ \mathrm{N}}_3{ \mathrm{B}}_3{\mathrm{Cl}}_3( \mathrm{A})\text{ with }{\mathrm{LiBH}}_4$  in THF gives a compound(B).Further the reaction of (A) with three moles of methylmagnesium Bromide gives the compound C and D. Then the compounds B and C are respectively ___?

• A

  Boron nitride and MeBr

• B

  Borazine and Diborane

• C

  Borazine and ${\mathrm{H}}_3{\mathrm{N}}_3{\mathrm{B}}_3(\mathrm{Me}{)}_3$

• D

  Diborane and ${\mathrm{H}}_3{ \mathrm{N}}_3{ \mathrm{B}}_3{\mathrm{Cl}}_3$