Answer
Since $v \times B = 0$, the magnitude of the force on the electron is zero.
Work Step by Step
By the right hand rule, the magnetic field is directed perpendicular to the direction of the current. For example, if the current is moving in the +x direction, the magnetic field is directed in the +z direction.
If the direction of velocity is perpendicular to the direction in (a) and (b), then the velocity is parallel (or anti-parallel) to the magnetic field.
We can write an expression for the magnitude of the force on the electron:
$F = \vert q \vert ~v\times B$
Since $v \times B = 0$, the magnitude of the force on the electron is zero.
