In which resistor does the greatest current flow in a DC series circuit with resistances of 10 ohms, 15 ohms, 20 ohms, and 5 ohms?

In a DC series circuit, the current that flows through each resistor is the same, regardless of the resistance values. This is due to the fundamental characteristics of series circuits, where the total current is determined by the total voltage supplied and the total resistance in the circuit according to Ohm's law (I = V/R). In a series configuration, there is only one path for current to flow, so all components experience the same current.

When resistors are connected in series, the total resistance is the sum of all individual resistances. The voltage across the entire circuit is divided among the resistors based on their resistance values, but the current remains consistent throughout the circuit. Therefore, even though the resistors have different values (10 ohms, 15 ohms, 20 ohms, and 5 ohms), the same amount of current flows through each resistor.

This means that option stating all resistors have the same current flow is correct, reflecting the behavior characteristic of series circuits.