Correct answer: C. The engine is burning oil.
A vehicle can give off blue smoke from the exhaust when it is burning oil. Poor maintenance and worn engines are typical causes. This blue smoke is harmful to the environment and may be costly. Drivers should have the vehicle checked by a competent person.
This is an official-style question from the Safe and Responsible Driving 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 →