Which of the following describes how to calculate total resistance in series?

In a series circuit, the total resistance is calculated by simply adding together all the individual resistance values present in the circuit. This is because, in a series configuration, the current flows through each resistor one after the other, and the total opposition to the flow of current is the sum of the resistances.

The formula you would use is:

Total Resistance (R_total) = R1 + R2 + R3 + ... + Rn

where R1, R2, R3, ..., Rn are the individual resistances in the circuit. This method reflects the cumulative effect of resistance in the path of current flow, as each resistor adds its resistance to the overall circuit.

Other methods or concepts, such as focusing on just the highest resistance, using a formula for parallel resistance, or subtracting resistance values, do not apply to series circuits. Each of those methods has distinct applications in different types of circuits, thus reinforcing that total resistance in series relies specifically and solely on the summation of all resistances present.