Step 1: Understanding the Concept:
This question asks for the main purpose or primary goal of the author in writing the passage. We need to analyze the overall argument and structure to determine the author's intent.
Step 2: Detailed Explanation:
The passage is structured as a classic argument:
- Paragraph 1: The author acknowledges the opposing viewpoint by describing in detail why language exams are "frustrating and difficult" for graduate students. This is a concession.
- Paragraph 2: The author pivots with the phrase "Although these frustrations are understandable..." and then presents the core argument: language skills are essential for "adequate research," which is a key part of graduate education.
- Conclusion: The final sentence reinforces the main point: "...in spite of its frustrating aspects, the language examination process is an important component of graduate school education."
This structure is not just a summary (D) or a list of frustrations (A). The author's primary goal is to justify the existence of the language requirement despite its difficulties. This is an act of defense.
Step 3: Final Answer:
The author acknowledges the downsides but ultimately argues in favor of the system, making the overall purpose a defense of the language examination requirement. Therefore, option (C) is the correct answer.