Read the following article and answer the question by choosing from the options.

Guess what , I ' m not in shape , and I walked there and back . It was 5:30 by the time I got to campus , and after seven by the time I got back . Really , when I did finally get to campus , I did n't do anything because I do n't know where anything is , and I was pretty darn exhausted . All I did on campus was use a drinking fountain and call my brother and rest on a lawn .

Why is the narrator so tired ?
Possible answers:
[A]. They were studying all night at the campus library .;
[B]. They are not in great physical condition .;
[C]. They went to the campus library and studied all night .;
[D]. None of the above choices .;...A:
[B].