Understanding Evolutionary Arms Races

The concept of evolutionary arms races is important in understanding the dynamic relationships between competing species. An evolutionary arms race occurs when two or more species exert selective pressures on each other, leading to reciprocal adaptations. A classic example is the relationship between predators and prey, where adaptations in one species lead to counter-adaptations in the other. Consider a scenario where a species of plant develops a toxin to deter herbivores. In response, a group of herbivores may evolve resistance to this toxin. Which of the following pairs of species interactions best exemplifies this process of evolutionary arms races?