Which of the Following Is an Explanation

Which of the following is an explanation?

A) Because I bought a gym membership, I will be much fitter by this time next year.
B) Since the founding of this country, there have been 44 presidents.
C) After the thief left, my jewelry was missing.
D) Many North American species went extinct as a result of the saber-toothed cat.
E) I have not spotted a red squirrel since I arrived at the park.