Correct answer: C. To start the engine.
The primary purpose of the battery is to start the engine. When the engine is running, it produces its own electricity to charge the battery and run the various electrical components, including lights, heating, radio and so on.
This is an official-style question from the Technical Matters topic of the Ireland driver theory test (Cat. B). Practise all 807 questions free on iTest.ie — with timed mock exams, automatic mistake tracking and progress sync across devices.
Practise the full question bank free →