Those required to undergo breathalyser tests are...

A)only drivers of cars and mopeds.
B)only road users who are involved in a traffic accident.
C)vehicle drivers who are required to do so at preventive checkpoints.Correct
All vehicle drivers are required to undergo the tests established for the detection of possible alcohol intoxication. Refusal to undergo such tests constitutes a serious offence of disobedience punishable under the penal code.

Authority agents responsible for traffic surveillance may subject the following to such tests:
- Any road user or vehicle driver directly involved as a possible party responsible in a traffic accident.
- Those who drive any vehicle with evident symptoms, manifestations that indicate or facts that reasonably allow the presumption that they are doing so under the influence of alcoholic beverages.
- Drivers who are reported for committing any of the traffic regulation offences.
- Those who, while driving a vehicle (including a bicycle), are required to do so by the Authority or its agents within the framework of preventive breathalyser control programmes ordered by said Authority.
- Other road users when they are involved in a traffic accident.