Final answer:
The punctuation needed in the sentence "Scientist arent exactly sure why cats go crazy around it." is after "Scientist."
Step-by-step explanation:
The correct answer is option A. After "Scientist". The sentence should be written as: "Scientists aren't exactly sure why cats go crazy around it." The subject in this sentence is "Scientists," which refers to a group of scientists. Therefore, the word should be pluralized. Additionally, the word "aren't" is a contraction of "are not" and requires an apostrophe to indicate the missing letter "o."