8. To compare the size of two countries' economies, we rst need to convert each country's GDP to a common currency using and then adjust for (A) (B) (C) price level differences; the interest rate the interest rate; the exchange rate the exchange rate; price level differences (D) the exchange rate; the interest rate (E) the interest rate; scal policy 9. The economic principle of diminishing marginal product of capital is represented by the mathematical assumption that the production technology (A is always increasing (B is always decreasing (C (D is convex with respect to capital 1 l ) is concave with respect to capital J ) \"E5 is continuously differentiable