Find the radius of the circle x² + y² = 25.

Correct option is B

the standard equation of a circle = (x-h)² + (y-k)² = r²
Where (h,k) is the coordinates of the circle's centre and r is the radius.
Comparing the given equation with the standard equation of the circle ,
Then
x² + y² = 25
x² + y² = 5²
then the radius = r(radius) = 5