Different people have different hobbies(业余爱好).For example, some people like reading, some like swimming and some like collecting(收集)things.In the pastI loved reading books and drawing pictures because by reading books I could learn many new things. Now traveling is my favorite.I enjoy visiting many different places of interest.I can learn a lot about people,places and history. It’s very interestingIhave many good friends.They all have their hobbies. Mary studies very hard, and her hobby is reading. Tony loves physical work,and his hobby is gardening.He usually plants flowers and trees in his yard.Judy is a quiet girl.She likes knitting. She likes to knit sweaters for her dolls. We all have different hobbies. but we arc still good friends( )I could learn many new things___
选项：

A:by traveling
B: by gardening
C: by reading books
D: by knitting