Final answer:
Despite its high reactivity, magnesium is used in construction primarily due to its low density, making it suitable for lightweight alloys, and its ability to form a protective passivation layer. Option b
Step-by-step explanation:
Magnesium is a highly active metal known for its ability to burn with a brilliant light; however, it still finds use in construction because of certain properties that mitigate its reactivity. The primary reason for its use is its low density, making it the lightest among widely used structural metals.
When exposed to air, the metal forms a protective layer of magnesium oxycarbonate, inhibiting further reaction, a process known as passivation. This characteristic, along with being malleable and ductile at high temperatures, makes it suitable for lightweight alloy production used in various industries, including construction. Option b