Step-by-step explanation:
According to the right-hand rule, if an electron moves in a negative x direction (to the left) and enters a magnetic field in the negative y direction (downward), the magnetic force on the electron will be in the direction of the positive z-axis or upward.
The right-hand rule states that if you point your right thumb in the direction of the velocity of a positive charge (or the opposite direction for a negative charge), and you point your fingers in the direction of the magnetic field, then the direction in which your palm faces represents the direction of the magnetic force acting on the charge. In this case, with the electron moving to the left and the magnetic field pointing downward, your fingers would point downward, and your palm would face upward, indicating that the magnetic force on the electron is upward along the positive z-axis.