Borazine, also known as inorganic benzene, can be prepared by the reaction of 3-equivalents of "$X$" with 6-equivalents of "$Y$". "$X$" and "$Y$", respectively are :

1. A $\mathrm{B}(\mathrm{OH})_{3}$ and $\mathrm{NH}_{3}$
2. B $\mathrm{B}_{2} \mathrm{H}_{6}$ and $\mathrm{NH}_{3}$ Correct answer
3. C $\mathrm{B}_{2} \mathrm{H}_{6}$ and $\mathrm{HN}_{3}$
4. D $\mathrm{NH}_{3}$ and $\mathrm{B}_{2} \mathrm{O}_{3}$