The first four Caliphs were Abu Bakr<span>, </span>Umar<span>, </span>Uthman<span>, and Ali
x</span>
The answer is B because they had a revolutionary leader so C is eliminated.
I hope this helps
The author who proposed the theory of "natural selection," which other people called "survival of the fittest" was named Charles Darwin. These two ideas are the founding basis of the theory of evolution.