To best support Bryan's claim that cities need farms more than farms need cities, you should focus on sentences that emphasize the dependence of urban environments on agricultural resources and the benefits that urban populations derive from nearby farms. Look for highlighted sentences that discuss the necessity of fresh produce, sustainability, food security, economic support for urban communities, or the agricultural services that contribute to city life.
If you provide specific highlighted sentences, I can help you determine which two are the most effective in supporting that claim.