Which statement about induced drag is true?

• A. It decreases as airspeed increases
• B. It increases with airspeed
• C. It is independent of lift
• D. It only occurs at high altitude

Answer: (A)

Induced drag is the drag that arises from producing lift, mainly due to wingtip vortices created as air flows around the wing. In level flight, as you speed up, you don’t need as large a lift coefficient to support the same weight, so CL falls and the strength of the wingtip vortices weakens. Since induced drag is proportional to CL squared and to 1 over the dynamic pressure (D_i ∝ CL^2/q, with q increasing as speed increases), increasing airspeed raises q and lowers CL, leading to a smaller induced drag.

So the true statement is that induced drag decreases as airspeed increases. It isn’t independent of lift (it’s directly tied to how lift is produced) and it doesn’t only occur at high altitude (it exists at all speeds and altitudes, though density affects the actual value).