Copper in soil is usually toxic to plants, but some plants that grow near copper mines evolve copper tolerance. When copper-tolerant plants are grown in copper-free soil, they are outcompeted by the non-tolerant genotype. Which of the following principles does this scenario exemplify?

a.
The evolution of tolerance to copper resulted in a dependence on copper

b.
Evolution always maximizes the improvement or progress of a species

c.
Evolutionary changes can be advantageous under some environmental conditions but disadvantageous under others

d.
Resistant phenotypes always out-compete non-resistant phenotypes