Answer: L
Step-by-step explanation:
see in the picture, L is belong to the perpendicular bisector of RS
=> LR = LS (1)
L is belong to the perpendicular bisector of ST
=> LS = LT (2)
from (1)(2) => LS = LT = LR
=> L is equidistant from the points R, S, T
=> L is the center of circle
