Final answer:
If the plant population was wiped out in a food chain, it would have cascading effects on the other members of the food chain, leading to a decrease in the populations of grasshoppers, mice, and snakes.
Step-by-step explanation:
If the plant population was wiped out in a food chain, it would have cascading effects on the other members of the food chain. Since plants are the primary producers, they are the source of energy for herbivores, which are then consumed by carnivores. If plants were wiped out, the herbivores would have a decreased food source, leading to a decrease in their population. This would in turn affect the population of carnivores, as they would have less prey to feed on. Therefore, option d) The populations of grasshoppers, mice, and snakes would decrease is the correct answer.