In an advanced lab, students set up an experiment in which streams of electrons and protons are separated by a very short distance and generated parallel to each other. The electrons and protons are moving in the same direction. Which of the following statements is a correct analysis about the motions of the electrons and protons and provides a supporting principle?
(A) The moving electrons and protons represent currents in opposite directions; thus, they will exert a magnetic force that will be in the opposite direction of their electrostatic force.
(B) The moving electrons and protons represent currents in opposite directions; thus, they will exert a magnetic force that will be in the same direction of their electrostatic force.
(C) The moving electrons and protons represent currents in the same direction; thus, they will exert a magnetic force that will be in the opposite direction of their electrostatic force.
(D) The moving electrons and protons represent currents in the same direction; thus, they will exert a magnetic force that will be in the same direction of their electrostatic force.
(E) The moving electrons and protons exert no magnetic force on each other.

Electron and protons represent current in opposite direction as they have opposite charges on it. Due to motion of electron and proton in electric field they will produce the magnetic field. As both are moving parallel it means they generate the magnetic field which is in the same direction as of their electrostatic force.

Option B is correct:

The moving electrons and protons represent currents in opposite directions; thus, they will exert a magnetic force that will be in the same direction of their electrostatic force.