Which of the following is a prediction consistent with the logic of the gravity model?

If China and Russia account for 42 percent of the world's gross domestic product, then trade between the two countries will be significant.

If Peru and Columbia jointly account for 20 percent of the world's gross domestic product, then they will only trade with low income nations.

A nation will trade with low income nations because their exports are cheaper than those of high income nations.

If Mexico accounts for 90 percent of the world's gross domestic product, then it will not engage in international trade due to market power.