Which condition must be met for an aircraft to successfully land?

For an aircraft to successfully land, it is essential that its weight is less than lift. Lift is the upward force produced by the wings as air flows over them, and this force must always counteract the weight of the aircraft during landing. When the aircraft approaches the ground, the goal is to create a situation where the lift generated is still able to support the weight of the aircraft, but typically less than its total weight to allow for a controlled descent and touchdown.

If the weight is greater than lift, the aircraft would be in a state of descent that could result in a hard landing or crash. Conversely, if lift is sufficient to exceed the weight, the aircraft remains airborne and could potentially stall if the lift decreases unexpectedly, which is dangerous during landing.

Therefore, ensuring that weight is less than lift helps the aircraft land safely and under control, making it the correct condition for a successful landing. This is why the other options do not accurately reflect the requirements for landing; they focus on relationships between forces that do not directly facilitate a safe touchdown.