Which of the following is the chief source of spontaneous combustion aboard tankers?

Correct Answer: Option B — oil soaked rags or rubbish

Spontaneous combustion occurs when oil-soaked rags or rubbish undergo oxidation, generating heat that cannot dissipate. If the material reaches its ignition temperature, it will ignite without an external spark. This is a major fire hazard aboard tankers and requires strict housekeeping and proper disposal of oily waste.