The correct answer is B. Lead pencils have no lead in them. The core of a lead pencil is actually made of graphite, which is a form of carbon. Graphite is a soft material that can be easily rubbed off onto paper, leaving a dark mark. The reason why lead pencils are called “lead pencils” is because they were originally made with lead. However, lead is a toxic metal, so it was replaced with graphite in the 18th century.
Option A is incorrect because lead pencils do not contain lead.
Option C is incorrect because lead pencils do not contain 70% lead.
Option D is incorrect because lead pencils do not contain 100% lead.