Answer:
a. Copper contamination in the soil created copper-tolerant plants.
Step-by-step explanation:
Those plants that are cultivated on the soil having high concentration of copper in the soil creates tolerance to copper and becomes copper tolerant crops. Copper is a metal which is required for the process of photosynthesis and component of many enzymes but excess amount of copper cause damage to the plants especially root tips. But there are several plants which are tolerance to high amount of copper in the soil such as monkey flowers.