Under "fire" insurance, which situation results in an insurer obligation to pay for loss?

In the context of fire insurance, the insurer has an obligation to pay for loss when damage is directly caused by a fire event as defined in the policy. Fire insurance specifically covers loss or damage resulting from fire, including the spreading of fire to insured buildings.

When considering the situation presented in option B, fire damage to insured buildings during a rebellion is relevant because fire can easily spread during civil disturbances, which may lead to significant property damage. If the buildings are insured and the fire is a direct cause of the loss, the insurer is obligated to fulfill its coverage responsibilities under the terms of the policy, assuming all other conditions and exclusions are met.

The other options, while involving scenarios that may result in damage, do not fall under the specific coverage of fire insurance. Damage caused to an appliance during a power surge does not qualify as fire damage. Similarly, radioactive contamination and loss of property from heat application are not situations where fire insurance would typically apply, as they are outside the perils covered by standard fire policies.