The correct answer is osmium (Os). It has an atomic mass of 190.23, which is higher than the atomic masses of platinum (Pt), lead (Pb), and tungsten (W).
Osmium is a very dense, hard, and brittle metal. It is the densest element at standard temperature and pressure, and the second densest element overall, after iridium. Osmium is also the most corrosion-resistant metal, and it is used in many applications where high durability is required, such as in electrical contacts and spark plugs.
Platinum is a silvery-white, ductile, and malleable metal. It is one of the most precious metals, and it is used in jewelry, dentistry, and electronics. Platinum is also a good catalyst, and it is used in catalytic converters and fuel cells.
Lead is a soft, malleable, and ductile metal. It is a relatively poor conductor of electricity, and it is used in batteries, ammunition, and radiation shielding. Lead is also a toxic metal, and it can cause lead poisoning if ingested.
Tungsten is a hard, brittle, and silvery-white metal. It is the heaviest element that is commonly used in industry, and it is used in many applications where high strength and resistance to wear are required, such as in light bulbs, X-ray tubes, and electric motors.