Final answer:
The course of an electric current is directly changed by resistance. Factors such as temperature and conductivity also indirectly affect the current by altering the resistance of the material through which the current is flowing.
Step-by-step explanation:
Factors Affecting Current Flow
Once a current is set in motion, it can have its course changed by various factors. The most direct answer to the question would be Resistance (Option B). Resistance is the property of materials that impedes the flow of electric current. An increase in resistance would cause a reduction in current, assuming the voltage remains constant. The relationship between voltage, current, and resistance is defined by Ohm's law, which states that the current (I) through a conductor between two points is directly proportional to the voltage (V) across the two points and inversely proportional to the resistance (R) of the conductor (I = V/R).
Other factors that would affect the current indirectly include temperature, as resistivity and hence resistance of materials changes with temperature. This is because higher temperatures cause atoms in conductive materials to vibrate more, which increases the number of collisions between electrons and atoms, effectively increasing resistivity. On the other hand, conductivity, which is the inverse of resistivity, also affects current flow. Materials with higher conductivity allow easier flow of electric current. These considerations are important in understanding and designing electrical circuits.