we know that
the equation of the circle into center-radius form is equal to
[tex](x-h)^{2} +(y-k)^{2}=r^{2}[/tex]
where
[tex](h,k)[/tex] is the center of the circle
[tex]r[/tex] is the radius of the circle
in this problem we have that
The center [tex](h,k)[/tex] is the point L
The radius [tex]r=SL=LM[/tex]
therefore
the answer is the option B
L
