Where is direct current typically found?

Direct current (DC) is typically found in fixed installations requiring stable voltage because it provides a constant voltage level that is essential for many electronic devices and systems. This stability is crucial in applications such as battery-powered equipment, where consistent power delivery is necessary for optimal performance.

In many instances involving electronic circuits, a stable voltage is fundamental to operation, which is why devices like solar panels, batteries, and certain types of electrical appliances utilize direct current. These systems rely on the characteristics of DC, which include a unidirectional flow of electric charge, to maintain efficient and reliable operation.

While it's true that portable devices often use direct current, the context of this question emphasizes fixed installations, which are designed specifically for environments that require a steady voltage without fluctuation, making option B the most suitable choice.