Which two factors affect the speed of current flow?

The correct answer is based on fundamental principles of electrical engineering. The speed of current flow, or the rate at which electric charge moves through a conductor, is influenced primarily by the material type and its properties, including resistivity. Different materials allow current to flow at different speeds due to their atomic structure and the availability of free electrons for conduction.

Temperature is also an influential factor, as it affects the resistance of materials. However, in this context, the combination that includes material type and another relevant factor, which would be generally understood as affecting the flow of electricity in a more indirect manner, would indeed relate to voltage, but primarily it is the material that allows the current to flow efficiently.

Thus, while voltage does play a role in driving current through a conductor, the intrinsic properties of the material are what primarily govern how quickly that current can propagate. Therefore, the answer emphasizes the importance of both the type of material and the influence of voltage in determining how current flows within that material.