Which of the following is a fragment?

a. One Direction is having a reunion.
b. Ms. Tyskewicz liked One Direction when she was in middle school.
c. Their reunion is good news.
d. Because Harry Styles.
(fragment: a word group that lacks a subject or a verb and that does not show a complete thought. Because fragments are incomplete thoughts punctuated as complete ones, they can confuse readers and must be avoided.)