Hello, could someone help me to understand why the answer is C for the question?

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How to Ask Better GRE Questions on Forums

Welcome to the forums! Since GregMat (who is a very chill person) doesn’t have any specific formatting rules when it comes to asking questions on the forums, I feel like there should at least be a reference text of some sort that can help people ask better questions and make the process more enjoyable for those who try to answer them. The Golden Rule: Imagine You’re Trying To Answer the Question Before you post your question about GRE preparation, practice questions, or strategies, try to put y…