An important challenge to traditional (pre-1860) ideas about species was the observation that seemingly dissimilar organisms, such as hummingbirds, humans, and whales, have similar skeletal structures. this most directly suggested to biologists that

Complete question:

An important challenge to traditional (pre-1860) ideas about species was the observation that seemingly dissimilar organisms, such as hummingbirds, humans, and whales, have similar skeletal structures. This most directly suggested to biologists that .

a) only the best-adapted organisms can survive

b) advantageous changes can be passed along to offspring

c) most evolution occurs rapidly following a mass extinction

d) dissimilar organisms might have evolved from a distant, common ancestor

e) all of the above

d) dissimilar organisms might have evolved from a distant, common ancestor

Explanation:

Many dissimilar organisms, such as hummingbirds, humans, and whales share some structural similarities such as common basic skeletal structures present in their body parts. This led the scientist to conclude that organisms with several observable differences share common ancestors. This is why these dissimilar organisms have some similar homologous skeletal structures.

For example, the bones present in the forearms of humans and whales are the same irrespective of their different outer morphology. This suggests that humans and whales share common ancestors.  

wheres the answers ?

answer: - b cells

explanation: -

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.