单选题：A "full tree" of degree 3 (every non-leaf node has 3 children) h

A "full tree" of degree 3 (every non-leaf node has 3 children) has 61 nodes. Then its height $$h$$ is at most ____. Note: $$h=0$$ for a single node tree.



A.20
B.19
C.21
D.cannot be determined


答案：A