Correct answer: (1) Deer, (2) Rabbit, (3) Frog, (4) Rat
The correct set is the one where the organisms fit common trophic roles in a terrestrial food web: deer and rabbit are herbivores, frog is an insect-eater, and rat is a small omnivore/prey animal. The other options include animals that do not fit as neatly into the expected food-web positions.