You must not pass when...

Answer: B — There is a double solid line in your lane

The correct answer is that you must not pass when there is a double solid line in your lane. Double solid lines indicate that passing is prohibited in both directions. This is a crucial safety measure designed to prevent accidents that can occur when vehicles attempt to overtake in areas where visibility is limited or where passing could be dangerous. When you see double solid lines, it is vital to adhere to this rule as it helps maintain safety on the road by clearly designating areas where passing could lead to hazardous situations. Other choices, while they might have implications for driving behavior, do not specifically indicate a legal prohibition against passing like the presence of double solid lines does.