Answer
A, negative; B, negative; C, positive
Work Step by Step
According to the right-hand rule: if a positive particle is moving to the right in a uniform magnetic field that points out of the page, there will be a magnetic force in the downward direction. As we can see, particle C is deflected downward while particles A and B are deflected upward. Thus, A and B are negatively charged while C is positively charged.
