What does the word ember refer to?

The term "ember" primarily refers to a hot, smoldering fragment of wood that remains after a fire has burned down. It describes a piece that continues to glow and give off heat even when the flames have subsided. This quality makes embers significant in the context of a fire, as they can be used to rekindle flames or maintain warmth. By contrast, the other options describe different elements related to fire, such as coal, sparks, or tools, but do not encapsulate the specific definition and characteristic of an ember itself. Thus, B accurately captures the essence of what an ember is.