What materials are primarily used in the ERJ-145's airframe construction?

The airframe construction of the ERJ-145 primarily utilizes aluminum and composite materials. This choice is correct as aluminum is valued for its favorable strength-to-weight ratio, which is essential in aviation to enhance fuel efficiency and performance. The use of aluminum reduces overall weight while maintaining structural integrity, which is crucial for an aircraft's aerodynamic capabilities.

Composite materials are also employed in strategic areas of the ERJ-145 to further reduce weight. Composites offer high resistance to corrosion and require less maintenance compared to traditional materials. Their use allows for innovative design elements that can improve the aircraft's performance and durability.

In contrast, other materials listed in the options like steel and fiberglass, wood and aluminum, or plastic and steel alloys are not representative of the primary construction materials for the ERJ-145. Steel is generally heavier and less advantageous in the context of aircraft structural integrity, while fiberglass and wood are not typically used in modern commercial jet airframe design. Therefore, the combination of aluminum and composite materials defines the ERJ-145's efficient and robust airframe structure.