For which of the following situations would the order that items are chosen not matter?

finding the number of ways to choose 3 students out of a class of 30.
finding the number of ways to choose al, bob, and carl out of a class of 30 students.
finding the number of ways to choose 2 vegetables out of 10.
finding the number of ways to choose a carrot and broccoli out of 10 vegetables.
finding the number of ways to choose 4 letters out of 12.