A square board has an area of 144 square units. How long is each side of the board 

Given area of square$=144\text{sq}\text{.units}$

$s\times s=144$

$s^2=144\Rightarrow s=\sqrt{144}\Rightarrow s=\text{12units}$

A: $\sqrt{144}=\sqrt{12\times 12}=12$  

B: $12$

C: $\text{Successor of}\sqrt{121}=\text{Successor}\text{of}11=12$

D: $\text{Predecessor of}\sqrt{169}=\text{Predeccssor}\text{of}13=12$