Answer:
D. 6
Explanation:
The general equation for a circle centered at the origin (0,0) is:
[tex]x^2+y^2=r^2[/tex]Given the equation of the circle:
[tex]\begin{gathered} x^2+y^2=36 \\ \implies r^2=36 \\ r^2=6^2 \\ r=6 \end{gathered}[/tex]Thus, the radius of the given circle is 6.