Number of tetrahedral boron atoms in peroxoborate obtained by the following 
Reaction

$2{\mathrm{NaBO}}_2+2{\mathrm{H}}_2{\mathrm{O}}_2+6{\mathrm{H}}_2\mathrm{O}$

$\to {\mathrm{Na}}_2\left[{\mathrm{B}}_2{\left(\mathrm{OH}\right)}_4{\left({\mathrm{O}}_2\right)}_2\right]6{\mathrm{H}}_2\mathrm{O}$ sodium peroxoborate
 

• A

  2

• B

  3

• C

  1

• D

  0