Final answer:
Each of the given food chains shows four trophic levels. The first level is plants or algae, the producers. The second is herbivores or primary consumers, which eat the producers. The third level includes carnivores, or secondary consumers, which eat the herbivores. The last or fourth level is also made up of carnivores (tertiary consumers) which eat other carnivores.
Step-by-step explanation:
The question is asking to identify a food chain in the Yellowstone food web that consists of four trophic levels. A trophic level refers to a level or position in a food chain or ecological pyramid. It represents the position a plant or an animal occupies in a food chain. Here, the food chains are: a) Grass → Grasshopper → Mouse → Snake b) Algae → Fish → Bear → Eagle c) Trees → Deer → Wolf → Hawk d) Flowers → Bee → Frog → Owl. All these food chains show four trophic levels. In all the chains:
1st trophic level: producers
The first trophic level (base) is always made up of producers - these are organisms that create food, either plants or algae.
2nd trophic level: primary consumers
The second trophic level includes primary consumers that eat the producers - these are usually herbivores.
3rd trophic level: secondary consumers
The third trophic level is made up of secondary consumers which eat the primary consumers - these are carnivore which eat herbivores for example.
4th trophic level: tertiary consumers
Lastly, the fourth trophic level consists of tertiary consumers – these are higher level carnivores that eat other carnivores.
Learn more about Food Chain