In which of the following situations is overtaking on the left prohibited?

Overtaking an animal in harness is prohibited when it involves overtaking on the left. This rule is primarily in place to ensure the safety of both the animal and the driver. When approaching or passing animals, drivers must be particularly cautious, as animals can behave unpredictably, especially when they are startled. Overtaking on the left could pose risks, as the animal might move unexpectedly in the direction of the overtaking vehicle.

In contrast, overtaking bicycles, two-wheeled motor vehicles, or cars on a one-way street generally follows the standard overtaking rules, where passing is permitted on the left, as long as it can be done safely. In these cases, the risk factors involved are considered manageable when proper care is taken.