Which of the Following Is Most Clearly an Explanation, Rather

Which of the following is most clearly an explanation, rather than an argument?

A) The war began due to an argument over control of the river.
B) Considering that there is no liquid water on Mars, there cannot be life there.
C) We can't get mom a puppy for her birthday, since she is allergic to dogs.
D) It is time to raise the taxes on imports, because domestic producers are finding it harder to compete with foreign goods.
E) Since the table and chairs in the dining room are wooden, we can't put up plastic shelving in that room.