Final answer:
The mechanical advantage of a teeter-totter with each seat 2 meters from the fulcrum is 1:1; however, this ratio is not present in the provided options, indicating a possible error in the question.
Step-by-step explanation:
The mechanical advantage (MA) of a simple machine like a teeter-totter (seesaw) is the ratio of the output force to the input force. In the case of a teeter-totter that is symmetrical, with both sides being an equal distance from the fulcrum, the mechanical advantage is determined by the ratio of the distances from the fulcrum where the forces are applied. Since both seats are 2 meters from the fulcrum, the mechanical advantage is simply the ratio of the distances, which is 2 meters divided by 2 meters.
Therefore, the mechanical advantage of a teeter-totter built so that each seat is 2 meters from the fulcrum is 1:1, which is not listed in the provided options. If the question intends for the options to represent the mechanical advantage, there may be an error, as none of the options correctly state a 1:1 ratio. The mechanical advantage in this case implies that the forces needed on each side to balance the seesaw are equal.