Invertebrate doesn't posses "Backbone" whereas Vertebrate chordate have that. That's the only & most important difference between them.
Hope this helps!
Answer:
B
Explanation:
It represents the greatest amount of cell differentiation for the newly formed organism.
Here all the organs and system get initiation and cell differentiate to form various organs.
The answer to your question is <span>B. Natural selection acted on the variation that was present in the population.
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