Laws of motion

One end of a string of length l is connected to a particle of mass m and the
other to a small peg on a smooth horizontal table. If the particle moves in a
circle with speed v the net force on the particle (directed towards the centre)
is :
(i) T, (ii) l
mv T
2
− , (iii) l
mv +T
2
, (iv) 0
T is the tension in the string. [Choose the correct alternative].