Borazole is obtained by reacting ${\mathrm{B}}_2{\mathrm{H}}_6$ with

• A

  ${\mathrm{NH}}_3$ is the ratio 1 : 2

• B

  ${\mathrm{NH}}_3$ in the ratio 2 : 1

• C

  ${\mathrm{NH}}_3$ in the ratio 1 : 4

• D

  cannot be formed