When is it illegal to pass another vehicle?

Answer: B — When there is a solid yellow line on your side

Passing another vehicle is illegal when there is a solid yellow line on your side of the roadway. This solid line serves as a clear visual indicator that passing is not permitted due to safety concerns. It usually signifies that the traffic flow is such that visibility is limited, or conditions may not be safe for overtaking another vehicle. Passage safety is a critical consideration for road users, and a solid yellow line indicates that the area ahead may not afford enough room to pass safely, either due to curves, hills, or oncoming traffic. Therefore, adherence to this marking is essential to ensure the safety of all road users, as attempting to pass when such a line is present greatly increases the risk of collisions. While passing is also subject to other considerations, such as road conditions or the action of the vehicle ahead, the clear regulations surrounding the solid yellow line make it unambiguous that passing is illegal in such scenarios.