The correct answer is B. Magnetite.
Bauxite is an ore of aluminum. It is the most important ore of aluminum, and is the primary source of aluminum metal. Bauxite is a mixture of aluminum oxides and hydroxides, with the most common being gibbsite, boehmite, and diaspore.
Magnetite is an iron ore. It is the most important iron ore, and is the primary source of iron metal. Magnetite is a black, iron-rich mineral with a high magnetic susceptibility. It is the most common magnetic mineral, and is found in many different types of rocks.
Lignite is a type of coal. It is the lowest rank of coal, and is also known as brown coal. Lignite is formed from plant material that has been buried and subjected to heat and pressure for millions of years. It is softer and has a lower energy content than other types of coal.
Nitrite is a salt of nitric acid. It is a white, crystalline solid that is soluble in water. Nitrite is used as a preservative, and is also used in the production of explosives and fertilizers.
Therefore, the correct answer is B. Magnetite.