Which is a characteristic of thermal explosives?

The characteristic of thermal explosives that makes option B the correct answer is based on the fundamental nature of these explosives. Thermal explosives are designed to operate through an exothermic chemical reaction, which means that they generate heat as they react. This heat production is a crucial aspect of their effectiveness, as it contributes to their capability to perform work, such as breaking rock or demolishing structures.

In contrast, the other options do not accurately describe the characteristics of thermal explosives. For instance, the requirement for cold temperatures is not aligned with how thermal explosives function, as they actually thrive in environments where heat is generated. Additionally, the notion that thermal explosives are only utilized in mining operations is incorrect; these explosives have a wider range of applications beyond mining, including construction and demolition. Lastly, the claim that thermal explosives have no safety risks is misleading; like all explosives, they come with inherent risks that must be managed through proper safety protocols and training. Thus, the focus on heat generation during their chemical reaction is a defining and correct characteristic of thermal explosives.