Paragraph 2: Until 1828, few people knew how to ignite anthracite and use it for fuel. That was because anthracite was so compact that no ordinary flame could make it burn. Then, a Scotsman named James Neilson invented the hot blast furnace. The air produced in the first chamber of the furnace was blown over anthracite located in the second chamber. That hot air caused the surface of the anthracite to ignite. Because anthracite was so dense, it could produce enough heat to melt iron ore. It was also plentiful, and a little went a long way, which lowered the cost of iron production. Once the hot blast technique was perfected, anthracite was in demand all over the world. In the United States, anthracite was found exclusively in Pennsylvania. As a result, Pennsylvania's mining industry boomed during the nineteenth century. In the twentieth century, when newer fuels replaced anthracite, the black gold rush ended and most anthracite mines were abandoned. According to the information in paragraph 2, why is anthracite able to produce a significant amount of heat?
A. because it is easily ignited

B. because it is dense and compact

C. because it is a plentiful type of coal

D. because it is a cheap source of energy