Write the structure of boric acid

Boric acid is better represented as $B(OH)_3$ where boron is bonded to three hydroxyl groups.

Hybridization of boron

• Boron forms three $\sigma$ bonds with three oxygen atoms.
• There is no lone pair on boron in $H_3BO_3$.
• Hence, the steric number of boron is $3$.

Therefore, boron has trigonal planar geometry and is $\boxed{sp^2}$ hybridized.

Hybridization of oxygen

Consider one oxygen atom in an $-OH$ group:

• It makes two $\sigma$ bonds: one with $B$ and one with $H$.
• It has two lone pairs.

So, the steric number of oxygen is $2\text{ bond pairs} + 2\text{ lone pairs} = 4$

Hence oxygen is $\boxed{sp^3}$ hybridized.

Match with options

• Boron: $sp^2$
• Oxygen: $sp^3$

So the correct option is $\boxed{\text{D: } sp^2 \text{ and } sp^3}$

Compare with stored correct answer

Stored correct answer = D

Our derived answer = D

Therefore, they agree.