Biot-Savart law indicates that the moving electrons (velocity $\vec{v}$) produce a magnetic field $\vec{B}$ such that:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $\vec{B} \perp \vec{v}$
The magnetic field produced is always perpendicular to both the velocity vector v and the vector from the current element to the point where magnetic field is being calculated.