The correct option is A Snake
Consumers in a food chain are those which depend on each other and on producers to sustain their lives. Almost all plant species are not consumers, but, are producers. Plant species like cactus and aloe vera, produce food using photosynthesis from the Sun's energy. They could be consumed by insects or rodents like mouse, which in turn, might be eaten by higher species in the food chain like snakes and eagles. Therefore, a snake is always a consumer in any food chain.