2020 Reading Comprehension - Main Idea

Which one of the following statements best reflects the critical message of the passage?

• For introducing any foreign plant into a country, the soil and climate conditions of that country should be suitable.
• As a staple food of a country, tuber crops like potato cannot replace cereal crops.
• Some of the fungal infections of plants cannot be prevented or stopped from spreading across large areas.
• Relying on a homogeneous food source is not desirable.