A tire company wants to determine if tires made with a new type of tread will last longer than the tires made with the original type of tread. The company has access to 24 different vehicles. The vehicles will be driven for one year and the depth of the remaining tread will be measured. The average depth for the new type of tread will be compared to the average depth of the original type of tread. Which of the following describes a matched pairs design for this experiment?

Each of the 24 vehicles is numbered 1–24. These numbers are put into a random number generator. The first 12 unique numbers generated will represent the vehicles that will receive the tires with the new tread. The remaining 12 vehicles will receive the tires with the original tread.
There are six vehicles of each vehicle type: sedan, SUV, minivan, and truck. For each type, the vehicles will be numbered 1–6, and a random number generator will be used to pick three unique numbers. These three vehicles will receive tires with the new tread and the other three vehicles in the group will receive tires with the original tread.
There are six vehicles of each vehicle type: sedan, SUV, minivan, and truck. Each vehicle type is numbered 1–4, and these numbers are entered into a random number generator. The first two unique numbers selected will represent the group of vehicles that will receive tires with the new type of tread. The remaining two groups will receive tires with the original type of tread.
The vehicles will be put into groups of two based on the size of the vehicle, with the largest two put together, the next largest two, etc. For each of the 12 groups of two, one of the vehicles is selected and a coin will be flipped. If it is heads, this car will receive tires with the new tread and the other vehicle will receive tires with the original tread. If it is tails, then the opposite will be done.