r (option A)
Explanation:[tex](\sqrt[]{r})^2[/tex]If the values of r are non negative, let r = 6
[tex]\begin{gathered} (\sqrt[]{6})^2\text{ = 6} \\ \text{The square cancels the square root} \end{gathered}[/tex]Hence, in this case the square cancels the square root and the result will be r.
So, for any non negative value of (√r²), the result is r (option A)
