The given question is incomplete it lacks the main question, group of choices, and dichotomous key, however, the correct question is attached as an image:
Answer:
The correct answer is - B) body shape
Explanation:
In this given dichotomous key, one can distinguish and identify the particular fish on their characteristics feature present in the diagram. In this chart, there are 9 different types of fish that share some characteristic features such as fins, stripes, the shape of tails, and others.
The body shape of the fishes is the best characteristic to begin the choice of keys here, the shape of fishes that are skinny and long and little fat and small in comparison helps in distinguish these fishes.
