The word "varsity" in the article means ______.

A．why a slang word is no longer slang
B．how to understand slang words
C．at what time a slang word is no longer slang
D．how slang words are used

A．Nobody has defined and recognized slang, although they are used by a generation after another generation.
B．Slang tends to be transient though they have found their way in dictionaries.
C．Having difficulty in defining slang and telling slang from similar things, people still use slang frequently.
D．Slang can be totally beyond the understanding of the old.