Since invasive species did not co-evolve with the other species in the ecosystem where they were introduced a. they can unbalance the ecosystem b. they are considered a serious environmental problem c. they lack natural predators to control their population d. all of the above

I believe the correct answer from the choices listed above is option D. Since invasive species did not co-evolve with the other species in the ecosystem where they were introduced they can unbalance the ecosystem, are considered a serious environmental problem and they lack natural predators to help control their population.