A particle with -q charge and mass m is moving at a \vec{v}=(v_{0}\frac{m}{s})\widehat{j} and entering a region with a uniform magnetic field \vec{B}=(B_{0}T )(-\widehat{j}) . Immediately after entering the magnetic field, the charged particles will:
a. Moving straightly accelerated
b. Moving straightly slowed down
c. Moving straight at a constant velocity
d. Stop and turn around
e. Moving in a circular path