Boric acid on heating at ${150}^{0}C$ gives

• A

  ${\mathrm{B}}_2{\mathrm{O}}_3$

• B

  ${\mathrm{H}}_2{\mathrm{BO}}_3$

• C

  ${\mathrm{HBO}}_2$

• D

  ${\mathrm{H}}_2{\mathrm{B}}_4{\mathrm{O}}_7$