a. There is no difference between the two circuit types.
b. In a series-parallel circuit, some components are connected in series and others in parallel, while in a parallel-series circuit, the opposite is true.
c. In a series-parallel circuit, all components are connected in both series and parallel, while in a parallel-series circuit, only some components are connected in both series and parallel.
d. In a series-parallel circuit, all components are connected in parallel, while in a parallel-series circuit, all components are connected in series.
Answer: b. In a series-parallel circuit, some components are connected in series and others in parallel, while in a parallel-series circuit, the opposite is true.