Answer:
B. sp2
Step-by-step explanation:
We see that there is a pi bond between one of the Oxygens when we draw out the Lewis Structure.
pi bonds are every bond other than a single bond. So double and tripple bonds.
To easily understand this, we can write out "sppp" and cross off however many pi bonds (p) there are. In this example we only have 1 pi bond so the hybridization will be sp2.