BR Physics 8.3b?
 

Can someone explain to me the solution? It has an electron with a vector moving it in a curvered way right and down. It asks which orientation of the the uniform electric field can explain the movement of the electron: right, left, up or down?

It's 8.4b on mine but it's okay.

The electron shown seems to be heading downward. An electric field is a field that's going from positive to negative. Since the electron is going down, it is attracted to positive charges that's coming from the bottom of the page. The E-field is + to -, so the top of the page has to be the negative side, so it repels the electron, a negatively charged particle. Thus, E-field has to point up.

I get it now. Thank you!