Question

wind tunnels: a test of form and function look up at the sky, and you are likely to see airplanes, helicopters, and other types of aircraft soaring high above you. what you might not realize is that these aircraft all had to pass a series of tests to be considered safe enough to fly. one tool that researchers use when testing aircraft is a wind tunnel. this essential machine helps scientists improve the design of aircraft. how wind tunnels work wind tunnels are tubes that vary in size depending upon the object being tested. airplanes require huge wind tunnels. at one end of the tunnel is a fan blowing air. the fan can be set to different speeds and directions. an object is held in place in the tube, either with physical restraints or with the use of magnets. then the fan blows air around the object, creating an effect similar to flying. wind - tunnel experiments help us understand how an object reacts to different wind situations. the tests can show how wind speed and direction affect the object while taking off, flying, and landing. researchers search for hidden flaws in the design of objects such as an aircraft. to help do this, they often add smoke or colored dye to the air. then the researchers photograph how the smoke or dye moves over the object while the fans are on. what is most likely the authors purpose for writing the passage? a to describe how the wind tunnels help scientists get new ideas for the future b to prove that wind tunnels are responsible for the success of nasa c to inform readers about an important tool researchers use to ensure the safety of all aircraft d to show how scientists at nasa developed the idea of the wind tunnel

Explanation:

The passage first introduces wind - tunnels as a tool for aircraft testing, then explains how they work and their benefits in ensuring aircraft safety. It doesn't focus on new ideas for the future, NASA's success, or the development of the wind - tunnel idea. It mainly aims to inform readers about wind - tunnels as an important tool for aircraft safety.

Answer:

C. to inform readers about an important tool researchers use to ensure the safety of all aircraft