The correct answer is: D. All the above.
The thickness design of the pavement is decided on the load carried by the main gears, nose wheel, and tail wheel. The main gears carry the most weight, so they need to be supported by a thicker pavement. The nose wheel and tail wheel carry less weight, but they still need to be supported by a thick enough pavement to prevent them from sinking into the ground.
The thickness of the pavement is also affected by the type of aircraft, the weight of the aircraft, and the frequency of use. For example, a heavier aircraft will need a thicker pavement than a lighter aircraft. An aircraft that is used more frequently will also need a thicker pavement than an aircraft that is used less frequently.
The thickness of the pavement is typically determined by a civil engineer. The civil engineer will consider the factors mentioned above and then design a pavement that is thick enough to support the load of the aircraft.