What happens to total drag if airspeed slows below L/D Max?

When the aircraft's airspeed slows below the point of maximum lift-to-drag ratio (L/D Max), total drag experiences an increase primarily due to increased induced drag.

As the airspeed decreases, the aircraft must generate the same amount of lift to counteract its weight, which requires a higher angle of attack. The induced drag is directly related to the angle of attack; as this angle increases, the induced drag also increases. This is because induced drag results from the creation of lift, and at higher angles of attack, the lift generation becomes less efficient, leading to additional drag.

In contrast, parasite drag consists of form drag and skin friction drag, and while it is generally affected by increases in airspeed, the primary factor at play as airspeed slows below L/D Max is the increase in induced drag due to the need for a higher angle of attack to maintain lift. Therefore, the correct answer highlights the relationship between slowing airspeed, increasing angle of attack, and the resulting rise in induced drag, which collectively lead to an increase in total drag.