The heuristic that allows one to see the problem from a different perspective and is most effective if there is a
specific endpoint
a. finding analogies
b. hill climbing
c. working backwards
d. trial and error

c. working backwards

Explanation:

It just is

your answer is "the 1950's"

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands