The correct answer is - 3.
The number 3 location is the one that is most suitable on this landscape for the emergence of water as a spring. The reason for that is that it is lowest point of the landscape on the image. Because the terrain falls towards this part, the rain that falls and manages to get into the ground, will be moving towards that direction. Since the land is coming to an end at the number three spot, and it is also falling downwards, the water will have no big problem to manage to penetrate through the ground and come out on the surface, as it will have a big pressure pushing from up towards down.
