.A simple pendulum consisting of a small object of mass m attached to a string of length l has a period T. A pendulum with which of the following combinations of object mass and string length will also have period T ?

a) Object Mass(m/2) String Length(l)
b) Object Mass(m) String Length(1/4)
c) Object Mass(root 2m) String Length (l/root2)
d) Object Mass (2m) String Length(4l)
e) Object Mass (4m) String Length (2l)