Final answer:
The garter snake is the resistant snake involved in the co-evolutionary arms race with the rough-skinned newts. The correct option is 3) The garter snake
Step-by-step explanation:
The resistant snake that is locked in a co-evolutionary arms race with the rough-skinned newts is the garter snake.
The garter snake has developed resistance to the toxin produced by the newts, allowing it to prey on them without being affected by their poison. This co-evolutionary arms race refers to the ongoing adaptation and counter-adaptation between the two species, where each species tries to outpace the other in terms of survival and reproduction.
For example, the newts may develop stronger toxins to deter the garter snake, while the garter snake may evolve increased resistance to these toxins. This back-and-forth process drives the constant evolution of both species. The correct option is 3) The garter snake