Q02-iv

Match the pairs in the following questions by writing the corresponding letters only.

$$\begin{array}{|c|l|c|l|} \hline A. & \text{The number of distinct binary tree} & P. & \frac{n!}{2} \\& \text{ with n nodes.}\\ \hline B. & \text{The number of binary strings of the length } & Q. & \binom{3n}{n} \\& \text{of 2n with an equal number of 0’s and 1’s} \\ \hline C. & \text{The number of even permutation of n } & R. & \binom{2n}{n} \\& \text{ objects.}\\ \hline D. & \text {The number of binary strings of length 6n } & S. & \frac{1}{1+n}\binom{2n}{n} \\& \text{which are palindromes with 2n 0’s.} \\ \hline \end{array}$$