When is it legal to pass another vehicle on a two-lane road in Missouri?

Passing another vehicle on a two-lane road in Missouri is legal when there is a dashed yellow line. This line indicates that passing is permitted, as it signals to drivers that they can cross into the opposing lane to overtake another vehicle if it's safe to do so. The dashed line allows for adjustments depending on traffic conditions, provided that the driver ensures there is ample space and no oncoming vehicles that could lead to a collision.

In contrast, the other options do not adequately reflect safe and legal passing practices. The idea that passing is allowed at any time overlooks the necessity of checking for oncoming traffic and road conditions, which is crucial for safety. Permitting passing only when there is no opposing traffic implies a restriction that does not account for the marking of the road lines, as passing is legal regardless of opposing traffic when the dashed line is present, provided it is safe. The stipulation that passing is allowed only when the speed limit is above 45 mph is misleading and does not conform to the actual laws governing road markings and passing zones.