A 2-3 is a type of tree which is having the following properties,

a. 2-3 tree’s all internal nodes have either two or three children.

b. 2-3 tree’s all paths from root to leaves have the same length

c. Then the number of internal nodes of a 2-3 tree having nine leaves could be 

A. 4 or 8 

B. 5 or 9 

C. 6 or 7 

D. 7 or 4