At an instant of time, a magnetic field is applied along the velocity of the particle. The acceleration produced in the particle will be

Zero

The correct answer is Option (4) → Zero

Explanation:

The magnetic force on a charged particle is given by $F = q(\vec{v} \times \vec{B})$.

If $\vec{v}$ is parallel to $\vec{B}$, then $\vec{v} \times \vec{B} = 0$, hence the magnetic force and acceleration are both zero.