Final answer:
OPTION A.The beam of electrons in a magnetic field directed towards the wall will be deflected upward, according to the right-hand rule used for determining the direction of magnetic force on moving charges.
Step-by-step explanation:
The subject of this question is physics, specifically pertaining to the effects of magnetic fields on moving charges. In this scenario, a beam of electrons is moving from right to left, and a magnetic field is directed towards the wall in front of you. According to the right-hand rule, the direction of the magnetic force on a negatively charged particle like an electron is opposite to that predicted by the rule (since it is designed for positive charges).
Thus, with the right-hand rule, your thumb would point in the direction of electron motion (left), your fingers would point in the direction of the magnetic field (toward the wall), and your palm would face the direction of force on a positive charge; but since electrons are negatively charged, the force will be in the opposite direction - upward. Therefore, the correct answer is: (a) Upward.