In which of the following situations, water cannot be used to extinguish fire ?
(A) Fire caused by wood
(B) Fire caused by electrical short circuit
(C) Fire caused by explosion in a car

Correct option is C

The correct answer is (B) and (C).
Extinguishing fire:
When there is any fire breakout water is poured on the fire. Water cools the combustible material so that its temperature is brought below its ignition temperature. This prevents the fire from spreading. Water vapors also surround the combustible material, helping in cutting off the supply of air. Hence the fire is extinguished.
The most common fire extinguisher is water. But water works only when things like wood and paper are on fire. If electrical equipment is on fire, water may conduct electricity and harm those trying to douse the fire. Water is also not suitable for fires involving oil and petrol. As water, sinks below the oil, it keeps burning on the top. For fires involving electrical equipment and inflammable materials like petrol, carbon dioxide (CO2) is the best extinguisher. CO₂, being heavier than oxygen, covers the fire like a blanket. Since the contact between the fuel and oxygen is cut off, the fire is controlled.