Concept:The radius is found by rewriting the circle equation in the standard form (x−h)2+(y−k)2=r2.Explanation:Divide the entire equation 3x2+3y2+6x−12y+6=0 by 3.This gives x2+y2+2x−4y+2=0.Group the x terms and y terms: (x2+2x)+(y2−4y)+2=0.Complete the square for x: x2+2x=(x+1)2−1.Complete the square for y: y2−4y=(y−2)2−4.Substitute back: (x+1)2−1+(y−2)2−4+2=0.Simplify: (x+1)2+(y−2)2=3.Comparing with (x−h)2+(y−k)2=r2, we get r2=3.Therefore, r=3.Answer:r=3, so the correct option is B.