In جَعَلَ لَكُمُ اللَّيْلَ وَالنَّهَارَ لِتَسْكُنُوا فِيهِ, what does لِتَسْكُنُوا explain?

Kay, Idhan, Hatta and Purpose Li

• The name of a place
• A past action by the listeners
• The owner of the night
• The stated purpose of making night and day