单项选择题
A.The code will compile without changes.
B.The code will compile if public Tree() { Plant(); } is added to the Tree class.
C.The code will compile if public Plant() { Tree(); } is added to the Plant class.
D.The code will compile if public Plant() { this("fern"); } is added to the Plant class.
E.The code will compile if public Plant() { Plant("fern"); } is added to the Plant class.
