Just choose 3
1) Lakes can form in hollows left by meteorite impacts (e.g. Clearwater Lakes, Quebec, Canada).
2) Lakes can form in the craters formed by volcanoes (e.g. Crater Lake, Oragon)
3) Lakes can form when a river is damed by a natural rock fall or man (e.g. Lake Mede)
4) Lakes can form where glaciers have scooped out the rock from the floor of a valley (e.g. Lake Geneva)
5) Lakes can form where block faulting lowers the land (e.g. lake Baikal)
6) lakes can form in natural depressions in the land (e.g. Lake Victoria)