When is it permissible to pass on the right?

Passing on the right is permissible when the vehicle in front is making a left turn and there is room to do so safely. This situation allows a driver to move to the right side of the road to pass because the left lane is occupied by the turning vehicle. It's important to ensure that this maneuver is safe and does not put other road users at risk, including pedestrians and cyclists who may be in the vicinity.

In the context of the other options, while driving on an empty road may seem like it would allow for passing anywhere, it doesn’t provide valid legal circumstances for passing on the right, which must align with specific traffic laws. Similarly, a higher speed limit does not necessarily create a situation where passing on the right is allowed; traffic laws must always be followed regardless of speed limits. Lastly, designated passing lanes are meant for overtaking slower vehicles, typically on the left, and do not permit passing on the right unless specific road markings and signs indicate otherwise. Therefore, option A is the only correct scenario where passing on the right is legally acceptable.