Final answer:
The correct answer is A. No Passing Zone Begins. This sign alerts drivers that they must complete any passing maneuvers before reaching the sign, as it marks the start of a zone where passing is not allowed.
Step-by-step explanation:
The sign that is placed on the left side of the highway to indicate that any passing maneuver must be completed before reaching this sign is known as 'No Passing Zone Begins'. This is a regulatory sign meant to inform drivers that they are approaching a stretch of road where passing other vehicles is prohibited due to line-of-sight restrictions, road conditions, or other safety considerations. It is essential for road safety that drivers adhere to this sign to prevent accidents caused by unsafe passing maneuvers in areas where visibility or road conditions make it dangerous to attempt such moves.