Which type of circuit connection allows for the highest total resistance?

A series connection is the correct choice for allowing the highest total resistance in a circuit. When resistors are connected in series, the total resistance is the sum of the individual resistances. This means that each additional resistor adds its resistance to the overall circuit, thereby increasing the total resistance proportionately.

In contrast, a parallel connection reduces total resistance, as the electrical current has multiple pathways to take, with each additional parallel path effectively decreasing resistance. In mixed or complex connections, which involve both series and parallel components, the behavior of resistance can vary, but the total resistance will still typically be lower than that of a purely series circuit due to the presence of parallel paths. Thus, the nature of series connections inherently leads to a greater cumulative resistance, making it the configuration with the highest total resistance among the options provided.