In recent years, a certain area of the world has experienced greater shifts in weather patterns. For example, there are many nights during which the temperature gets below freezing, but many days that are very warm. These shifts have made it difficult to grow and harvest crops.

The changing temperatures are environmental stresses that make it harder for crops to grow and survive. Crops with greater resistance to environmental factors are more likely to tolerate freezing nights and warm days. This matches choice B; resistance to diseases or insecticides would not directly address the weather shifts described.

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