Options are:
(a). studied in Peking University;
(b). talked with his friends about the walls;
(c). experienced the "cultural shock" at his arrival;
(d). spent two and a half years in China over several visits;

Read the following article and answer the question. Article: Having spent two and a half years in China over several visits, I don't remember ever going through a phase we in the United States call "cultural shock". This period of difficulty in adjusting to a new culture would probably have set in during my semester at Peking University. Of course, this is not to say that I didn't notice any differences between the American and Chinese cultures upon my arrival at Peking University, I did notice the differences. Looking back, I remember one of the first differences I noticed: Chinese universities are surrounded by walls. To an American, this is one of the most striking aspects of a Chinese university which immediately sets it apart from an American campus. Having grown up in the United States, I had never seen a university surrounded by high, cement walls. My idea of a university, based on having seen scores of them in different states of the U.S., was a place of life and learning, an inseparable part of the community in which it was located, open not only to the students of the school itself, but also fully accessible to students from other schools and to the broader public. My idea of a university was that it was a center of cultural life, a resource for the entire community. In all my twenty-one years, it had never occurred to me that a school would have a wall around it. Walls enclose and separate; schools expand and integrate . _ I asked a Chinese friend if all Chinese universities have walls around them. "You know, I have never really thought about it. I guess so. I guess all Chinese schools have walls around them, not just universities." "Why?" I asked, "What's the point?" "I don't know. To protect us, I suppose." "From whom?" "I don't know. Don't you have walls around your schools in the United States?" I thought carefully before answering. "No, I've never seen or heard of a university encircled by a wall." My Chinese friend seemed puzzled. Walls around schools came to strike me as more than just an architectural difference between the United States and China.... Question: The author felt strange about Chinese culture when he _ . Answer:
Answer:
(a).