An Electron Is Moving At $2.5 \times 106 \mathrm{~m} / \mathrm{s}$

An electron is moving at $2.5 \times 106 \mathrm{~m} / \mathrm{s}$ perpendicular to a uniform $3.5 \mathrm{mT}$ magnetic field. What is the radius of its path?

A) $4.1 \mathrm{~mm}$
B) $1.6 \mathrm{~cm}$
C) $3.9 \mathrm{~cm}$
D) $2.0 \mathrm{~mm}$
E) $5.1 \mathrm{~cm}$