Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

[EX Q]: Question: What type of species can alternate between medusa and polyp forms? Answer: cnidarian
[EX A]: As you can see in Figure below , both body plans have radial symmetry. Some cnidarian species alternate between medusa and polyp forms. Other species exist in just one form or the other.

[EX Q]: Question: Most food chains and webs have a maximum of how many trophic levels? Answer: 4
[EX A]: A trophic level is a feeding position in a food chain or food web. Most food chains and webs have a maximum of four trophic levels. There is less energy and biomass at higher trophic levels.

[EX Q]: Question: What is the attachment of ducklings to their mother an example of? Answer: imprinting
[EX A]:
Figure 45.39 The attachment of ducklings to their mother is an example of imprinting. (credit: modification of work by Mark Harkin).