Which of the following is a primary advantage of turbofans over turbojets?

The primary advantage of turbofans over turbojets is greater fuel efficiency. Turbofan engines are designed with a large fan at the front, which allows them to produce a significant amount of thrust through a combination of bypass air and core jet exhaust. This design leads to better fuel economy, especially at subsonic speeds, making turbofans more suitable for commercial aviation where fuel costs are a critical factor.

In comparison, turbojets are less fuel-efficient because their operation relies more heavily on the high-speed exhaust jet rather than bypass air. The ability of turbofans to sustain efficient operation at lower speeds and for longer ranges contributes to their dominance in the commercial and transport aircraft market. Thus, greater fuel efficiency is a defining characteristic that sets turbofans apart and is why this choice is correct.