A proton moving with velocity $\bf{v}$ in the plane experiences a force $\bf{F}$ $=q(\bf{v} \times \bf{B})$, where $q$ is the charge on the proton and $\bf{B}$ is a uniform magnetic field pointing directly out of the page. Which of the two vectors $\bf{F}_1$ or $\bf{F}_2$ in the figure below represents the force on the proton? Remember that $q$ is positive.

A. $F_1$
B. $F_2$