Why is the term post-structuralism preferred by most scholars to post-modernism, with which it was often used interchangeably?

A. The term underlines that post-structuralism is not confined to a particular post-modern period and is a position with shares more with its opponents, as scholar Waever argues.
B. Post-modernism connotes ‘anti-modernism,’ and post-structuralist theory is concerned with ‘modern’ events.
C. Post-structuralism has more letters.
D. Other international relations scholars were too overtly critical of ‘post-modern’ theories.