Final answer:
Genetically modifying crop plants to be herbicide-resistant can indirectly affect weeds by creating selective pressure, potentially leading to herbicide-resistant weed populations through natural selection.
Step-by-step explanation:
In the context of genetically modifying crop plants to be herbicide-resistant, this modification might indirectly affect weeds by creating selective pressure, potentially leading to herbicide-resistant weed populations through natural selection. The use of herbicide-resistant crops allows for the use of herbicides to control weeds without affecting the crop. Consequently, the herbicide-tolerant crops enable the use of reduced-risk herbicides that break down more quickly in soil and are non-toxic to wildlife and humans.