The class of fire on which a blanketing effect is essential to extinguish the fire is __________.

Correct Answer: Option B — class B

Class B fires involve flammable liquids. Blanketing agents, such as foam or CO2, are essential to exclude oxygen from the fuel surface, effectively breaking the fire tetrahedron. Water is ineffective and dangerous as it may spread the burning liquid, violating standard firefighting protocols for liquid fuel hazards.