question_answer

If \[{{(1+x)}^{n}}={{C}_{0}}+{{C}_{1}}x+....+{{C}_{n}}{{x}^{n}},\] then the value of \[\sum\limits_{r=0}^{n}{\sum\limits_{s=0}^{n}{{{C}_{r}}}}{{C}_{s}}\]is equal to r=0 s=0

A)  \[{{\text{2}}^{n}}~\]                        

B)  \[{{\text{2}}^{2n}}\]  

C)  \[{{\text{2}}^{2n+1}}~\]                  

D)  \[{{2}^{3n}}\]