Help!! I'm doing a lab report and am unsure which variables are independent, dependent, and controlled. My lab is due tomorrow

I did a lab where I took four cups and filled them each with 1/2 cup of water. I left one cup of water untouched. With the rest, I added 1 tsp of salt into one, 2 tsp of salt into another, and 3 tsp of salt in the last one. I then put them in the freezer and checked every 15 minutes for four hours to see if salt affects how water freezes.