In RNA-Seq Technology,it Is Stated That RRNA Is Discarded Before

In RNA-seq technology,it is stated that rRNA is discarded before analysis.Why do you think this is done?

A) rRNA will be abundant compared with other transcripts,potentially making their expression difficult to detect
B) rRNA binds to other transcripts and degrades them
C) rRNA cannot be converted to cDNA
D) rRNA is less stable than other RNA forms and will release small interfering fragments
E) none is a plausible reason