You are driving on a wide road on which oncoming traffic can pass by you, unobstructed. Within what distance must you be able to stop in any event?

The rule here is that when you are driving on a wide road and oncoming traffic can pass you without any problems, you must always be able to stop within the distance you can clearly see ahead—this is called the "sichtbare Strecke" or visible distance. This means you should only drive as fast as you can stop safely for any obstacle within your field of vision. This rule ensures you have enough time to react to anything unexpected on the road, keeping you and others safe. There is no need to reduce this distance to half or double it; you just need to be able to stop within what you can see. Your answer is correct.