Which of the following is an advantage of an impressed current system?

An impressed current system is advantageous because it can protect large areas with a single installation. This is due to its ability to provide a continuous and controlled flow of current to the metal surface, which helps to effectively mitigate corrosion over a much larger area compared to other systems like sacrificial anodes.

Impressed current systems utilize an external power source to drive the protective current, which allows them to be tailored for specific applications and achieve effective protection in various environments. This capability often makes them more efficient for large structures, such as pipelines, tanks, or ships, where extensive coverage is necessary.

In contrast, the highlighted disadvantages of other options reinforce why the chosen answer is correct. Regular replacement of components may be necessary in other systems, while the installation costs of sacrificial anodes can add up, particularly for extensive protection requirements. Additionally, while maintenance might be less frequent for impressed current systems compared to other forms of cathodic protection, stating they do not require maintenance would be misleading as some level of ongoing monitoring is usually needed to ensure the system operates efficiently.