Final answer:
Darwin's theory of evolution was controversial because it challenged established religious beliefs about the creation and immutability of species, which was central to many people's worldview in the 1800s.
Step-by-step explanation:
Charles Darwin's theory of evolution was highly controversial in the 1800s primarily because it contradicted religious beliefs. At that time, many people, including religious leaders, believed in the immutability of species and that the world was approximately 6000 years old, as per the biblical creation account. Darwin's theory proposed that species evolved over time through natural selection, which suggested that organisms change and that many had gone extinct, challenging the notion of a static natural world. This idea was in direct conflict with the belief in special creation by a deity, which was a fundamental aspect of religious doctrine. Hence, the correct answer to the question is "a) It contradicted religious beliefs". Despite initial resistance by some in the scientific community, Darwin's theory rapidly gained acceptance due to the accumulation of substantial evidence. By 1870, the majority of British scientists supported evolutionary theory, even before genetics was recognized as the mechanism behind it. Today, the theory is widely accepted among biologists, and any claims that it is still controversial within the scientific community are not based on actual scientific consensus.