Do you agree or disagree? Based on the gravity model, I would Part 4 A. agree. The gravity model predicts trade volume is proportional to the product of the GDPs of the trading partners and inversely related to the distance from each other. B. disagree. The gravity model predicts that trade volume is proportional to the ratio of the GDPs of the trading partners. The larger the difference in size, the larger the ratio, and the greater the trade volume. C. agree. The gravity model predicts trade volume is proportional to the product of the GDPs of the trading partners and directly related to the distance from each other. D. disagree. The larger the difference in size the more the countries will trade. Since Mexico is much smaller than the U.S., it makes sense that it trades largely with the U.S. Brazil is a much larger economy; therefore, it splits its trade with other large economies, such as the U.S. and the E.U