Final answer:
The highest capacitance is achieved when capacitors are connected in parallel, with three capacitors in parallel (option d) providing the greatest capacitance out of the given combinations.
Step-by-step explanation:
The combination of capacitors that has the highest capacitance when identical capacitors are used is when they are connected in parallel. For capacitors in parallel, the equivalent total capacitance is the sum of the capacitances of each individual capacitor. Since they are all identical, if n capacitors are connected in parallel, the total capacitance is n times the capacitance of one capacitor.
When capacitors are connected in series, the situation is different. The reciprocal of the total capacitance is the sum of the reciprocals of each individual capacitor's capacitance. This results in a total capacitance that is less than the capacitance of the smallest individual capacitor in the series.
In the options provided, two capacitors in parallel (option b) have a higher capacitance than two in series (option a), three in series (option c), and even more so than three capacitors in parallel (option d), which would provide the highest total capacitance of all options.