If the electric conductivity of the Earth's outer core is slightly decreased, then which one of the following is the most immediate effect?

The Earth's magnetic field is generated by the geodynamo process in the liquid outer core, which consists primarily of molten iron and nickel. This process relies on the convective movement of this electrically conducting fluid. According to the principles of electromagnetism, the strength of the induced magnetic field is directly proportional to the magnitude of the electric currents flowing through the medium. If the electrical conductivity of the outer core decreases, the resistance to current flow increases. Consequently, for a given amount of fluid motion, the resulting electric currents will be smaller. Since the magnetic field is maintained by these currents, a reduction in current leads to a weaker geomagnetic field. Magnetic reversals or changes in declination are complex phenomena involving long-term magnetohydrodynamic instabilities and are not the primary immediate consequence of a slight change in conductivity.