Diminishing marginal rate of substitution can be seen when indifference curves Naim 21:39 Microeconomic Theory Chapter 4 Diminishing marginal rate of substitution can be seen when indifference curves A) cross. B) are convex. C) are downward sloping. D) become flatter as we move down and to the right. Answer: become flatter as we move down and to the right. Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+