Why does Captain Von Trapp sing the song Edelweiss in the musical festival？

Why does Captain Von Trapp sing the song Edelweiss in the musical festival？
A.It is the most popular song at that time.
B.It stands for the love of motherlanD.C.；It is well-known by everyone.
D.It is easy to sing.
正确答案：It stands for the love of motherland.