Which of the following sentences contains formal language suitable for academic writing?

This choice includes subjective language, as the phrase "I believe" introduces personal opinion rather than an objective statement. Academic writing typically favors a more formal tone that avoids personal pronouns and subjective assertions, focusing instead on evidence and established findings.

While this sentence is mostly formal, the use of "who reside in Kansas" could be seen as somewhat informal compared to other more concise phrasings. Academic writing often favors brevity and clarity, suggesting that a more direct construction might enhance formality.

This statement, while formal, is somewhat convoluted. The phrase "do not support the rejection" could be simplified to "support the null hypothesis," which would clarify the meaning. Academic writing values clarity, and this sentence's complexity may detract from its effectiveness.