Which of the Following Is(are) Characteristic of Liabilities

Which of the following is(are) characteristic of liabilities?
#1 They must be unavoidable obligations.
#2 They are obligations that require settlement by a future transfer of cash, goods, or services.
#3 They must be settled by using cash, goods, or services that were earned by an entity in the performance of its normal business operations.
#4 The underlying transaction creating the obligation must have already occurred.

A) #1, 2, and 3.
B) #1, 2, and 4.
C) #2, 3, and 4.
D) #1, 3, and 4.
E) #1, 2, 3, and 4.