I get to class today , paper proudly in hand to realize .... that the due date was pushed back till Thursday , only I forgot to make the change in the calendar on my phone . Sigh . Oh , well .

Q with options: Give answer the following question using evidence from the above passage: Why may the due date of the paper have been pushed back ?
Pick from:
(A). The paper was more difficult than initially thought .;
(B). The teacher had a scheduling issue .;
(C). The students were having issues with their calendars .;
(D). None of the above choices .;
(A).