What must you look out for when the traffic lights turn green?

When a traffic light turns green in Germany, you do not have unconditional right of way. Before entering the intersection, you must check that pedestrians crossing the road have finished, and also ensure that other road users—such as motorcyclists coming from any direction—are not in your path. This is legally required because pedestrians may still be on the crossing and vehicles could still be completing their maneuvers. It is not necessary to yield to oncoming traffic if you are driving straight ahead and have a green light, unless you are turning left, but in the original question only pedestrians and the motorbike were relevant. That's why answers 1 (the pedestrian) and 2 (the motorbike) are correct—because both could cross your path and you must be sure it's safe before moving off on green. Always scan both ways and the crosswalk before proceeding.