The correct answer is option 4, Titanium. Titanium is a metal that is resistant to corrosion, making it suitable for use in environments with seawater, such as making boats. It has a high strength-to-weight ratio, which means it is strong and durable but also lightweight. This property makes it an excellent choice for boat construction as it increases fuel efficiency and enhances maneuverability.
Tungsten, option 1, is not used for making boats as it is a heavy metal and not resistant to corrosion, making it unsuitable for use in seawater.
Nickel, option 2, is also not commonly used for boat construction. While nickel does have good corrosion resistance, it is not as widely used as titanium in this context.
Antimony, option 3, is a metalloid that is brittle and not typically used for boat construction. It lacks the necessary properties, such as corrosion resistance and strength, to withstand the harsh conditions of seawater.
In summary, titanium is the best choice for making boats that will not corrode in seawater due to its high strength, lightweight characteristics, and corrosion resistance.