The correct answer is D. Pitchblende.
Pitchblende is a uranium ore that is the primary source of radium. It is a black, heavy, and radioactive mineral that is found in uranium deposits. Pitchblende is a complex mineral that contains a variety of elements, including uranium, radium, thorium, and lead. It is the most important source of radium, which is a radioactive element that is used in medical treatments and research.
Rutile is a titanium dioxide mineral that is found in igneous and metamorphic rocks. It is a common mineral that is used in a variety of applications, including paint, ceramics, and sunscreen. Rutile is not a source of radium.
Haematite is an iron oxide mineral that is found in igneous, metamorphic, and sedimentary rocks. It is a common mineral that is used in a variety of applications, including iron and steel production, pigments, and jewelry. Haematite is not a source of radium.
Limestone is a sedimentary rock that is composed of calcium carbonate. It is a common rock that is used in a variety of applications, including construction, agriculture, and water treatment. Limestone is not a source of radium.