Given a disfluent sentence, modify the sentence to it to its equivalent fluent form, preserving the meaning of the sentence.
One example: Who did the Han Chinese want to help the Khitan no I mean the Mongols fight?
Solution is here: Who did the Han Chinese want to help the Mongols fight?
Explanation: The input initially means Khitan and then changes to Mongols, hence this is correct.

Now, solve this: Which theory states that Charles Darwin no Earth's features remained unchanged after forming in one single catastrophic event?
Solution:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Which theory states that Earth's features remained unchanged after forming in one single catastrophic event?