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The traffic participants are obliged to notify the administrator of the public road or the nearest police unit when they become aware of the existence on the road of an obstacle or of any other dangerous situation for the flow and safety of traffic. It is not mandatory to emit acoustic signals or to signal the traffic participants who are driving from the opposite direction.

The correct answer is: C

Recommendations:

Obligations and prohibitions of the drivers of vehicles while driving - Audio-Video Lesson --> Road Traffic Code - Obligations, prohibitions and aggressive driving

For answers  A  and  B 

Regulation** - Article 112

The drivers of vehicles signal with the means of luminous, sound warning or with the arm, as the case may be, before carrying out any maneuver or for avoiding an immediate danger.

Regulation** - Article 113

(1) The means of sound warning must be used at a distance of at least 25 m from those they are addressed to, for a period of time that ensures the perception of the signal and without determining them to perform maneuvers that may endanger traffic safety.
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For answer  C 

Regulation** - Article 96

(1) The traffic participants are obliged to notify the administrator of the public road or the nearest traffic police officer when they become aware of the existence on the road of an obstacle or of any other dangerous situation for the flow and safety of traffic.
(2) Is prohibited the any person to throw, to leave or to abandon objects, materials or substances or to create obstacles on the public road. The person who could not avoid creating an obstacle on the public road is obliged to remove it and, if it is not possible, to signal its presence and to immediately notify the administrator of the public road and the nearest police unit.

** Regulation = REGULATION for the implementation of OUG 195/2002 updated (Road Traffic Code Regulation)