The correct answer is C. The two authors are in awe of nature; their experiences reveal that time in nature can change people.
Step-by-step explanation:
In grammar, the punctuation of a sentence mainly depends on the different components that are part of it and the way these relate, in the case of the sentence presented, this sentence contains two main ideas "The two authors are in awe of nature" and "their experiences reveal that time in nature can change people" which makes necessary to place a punctuation mark between both, considering both ideas express a complete thought and do not depend on the other to stand, this punctuation mark should be a semicolon (;) as one of the uses of semicolon is to separate complete or independent sentences. Additionally, these sentences are short and each simple sentences and therefore any other punctuation mark is required, this makes option C "The two authors are in awe of nature; their experiences reveal that time in nature can change people" the sentence that is punctuated correctly.