An electron is projected with uniform velocity along the axis of a...

The magnetic field inside a long current-carrying solenoid is uniform and directed along its axis.

The electron is projected with a uniform velocity along the axis of the solenoid, which means its velocity vector $\vec{v}$ is parallel or anti-parallel to the magnetic field vector $\vec{B}$.

The magnetic force experienced by a moving charge is given by $\vec{F} = q(\vec{v} \times \vec{B})$.

Since the angle $\theta$ between $\vec{v}$ and $\vec{B}$ is either $0^\circ$ or $180^\circ$, the cross product $\vec{v} \times \vec{B} = vB\sin\theta = 0$.

Therefore, the magnetic force acting on the electron is zero. In the absence of any force, the electron will not accelerate and will continue to move with its initial uniform velocity along the axis of the solenoid.

Answer: d