Final answer:
The force on a negative charge moving upward at an angle to the north in a magnetic field pointing north would be to the west, according to the left-hand rule for negative charges.
Step-by-step explanation:
The direction of the force on a moving charge in a magnetic field is given by the right-hand rule for a positive charge and the left-hand rule for a negative charge. According to the provided information, a positively charged object moving due west in a region where the magnetic field is due north experiences a force that is straight down. Therefore, if the charge is negative and moving in the same direction, the force would be in the opposite direction, meaning straight up.
Given that the charge is moving at an upward angle to the north, and the magnetic field also points to the north, the force will be perpendicular to both the velocity of the charge and the magnetic field direction. Since the magnetic field is horizontal, and the charge is moving upward, the only perpendicular direction to both is either east or west. Using the left-hand rule for a negative charge, the thumb points in the direction of the velocity (upwards to the north), the fingers point in the direction of the magnetic field (north), and the force direction, indicated by the palm, would be directed to the west.
Therefore, the correct answer to the question is: 3) west.