What action do flight crew members take to reduce lift as the aircraft descends?

Reducing speed and power is the appropriate action for flight crew members to take in order to decrease lift during the aircraft's descent. When an aircraft descends, maintaining a slower speed generates less lift, which helps to control the descent rate. The reduction in power, achieved by throttling back the engines, helps lower the altitude more safely and efficiently while also minimizing lifting forces.

In contrast, extending flaps increases lift, which is not desirable during descent. Turning off the fuel supply is not a viable action that would help manage lift and would indeed create critical issues for engine operation. Increasing altitude, of course, contradicts the goal of descending and would not contribute to reducing lift. Thus, the combination of reducing speed and power effectively allows the aircraft to control its descent while managing lift appropriately.