Question

the dipole is kept near an honest infinitely long straight wire Having uniform negative linear charge density

Answer 1

Here is a complete answer.

a & b: Cannot be true in any case. Because for the net force on a dipole to be zero, the field lines shoould be parallel to eachother and the dipole must be placed perpendicular to the field. However, in the case of a point charge you cannot have parallel field lines.

c: Not true again. Because in any orientation(except radial) the force on the positive and negative charge will form a couple and you WILL have torque

d: TRUE! if you place the dipole radial from the point object then there will be no net torque! Since torque= F*Rsin(theta). If it is radial sin(theta) is zero