As temperature decreases, what happens to True Airspeed (TAS) while climbing?

As altitude increases during a climb, the atmospheric temperature generally decreases in line with the standard lapse rate, which, under normal conditions, is around 2°C per 1,000 feet of altitude gained. True Airspeed (TAS) is a measure of the aircraft's speed relative to the surrounding air masses, and it is influenced by both indicated airspeed (IAS) and air density.

When the temperature decreases, the density of the air also decreases. Although the indicated airspeed may remain constant, the true airspeed will decrease because, at lower temperatures, the air becomes less dense. This reduction in air density affects the lift and drag characteristics of the aircraft. To maintain performance, the aircraft must account for this change, and thus, in colder conditions, true airspeed will reflect this nuance and decrease in response to the reduced air density.

Hence, in a climb with decreasing temperatures, true airspeed will decrease as a result of the changing air density, which is why the correct choice represents the expected behavior of TAS under these circumstances.