A string of length L and mass M is lying on a horizontal table. A force F is applied at one of its ends. Tension in the string at a distance y from the end at which the force is applied is
first find the linear mass density..which is M/L*(L-y)..
then the acceleration which is =F/M
tension in the string is the force applied by the first part on second..so f=ma
m=mass density * y
==>M/L*(L-y) * T/M =option 3