What uniform magnetic field applied perpendicular to a beam of electrons moving at $1.3 \times 10^6 m/s$, is required to make the electrons travel in a circular arc of radius 0.35 m?

$2.1 \times 10^{-5} G$ $6 \times 10^{-5} T$ $2.1 \times 10^{-5} T$ $6 \times 10^{-5} G$

$2.1 \times 10^{-5} T$

The correct answer is Option (3) → $2.1 \times 10^{-5} T$