Final answer:
Series resistors have the same current sequentially passing through them, while parallel resistors have leads connected together on each side.
Step-by-step explanation:
In a combination circuit, the series and parallel sections can be identified by examining the circuit diagram and how the current flows through the resistors. Resistors are considered to be in series if the same current passes sequentially through them, meaning the current flows from one resistor to the next. On the other hand, resistors are considered to be in parallel if the leads on one side of the resistors are connected together, and the leads on the other side are connected together.
For example, let's say we have a circuit with three resistors, R1, R2, and R3. If the current flows from R1 to R2 to R3, then R1 and R2 are in series, and R3 is in parallel to the series combination of R1 and R2.