If the beams of electrons and protons move parallel to each other in the same direction, then they
Repel each other
Step1: Electrons
Step2: Protons
Step3: If electron and proton beams move in the same direction, they are said to be parallel.
Protons are positively charged, while electrons are negatively charged. As a result, the currents they carry are in opposite directions. Therefore, they repel each other.
Hence, option B is the right answer.