There are some style guidelines to follow for an academically acceptable writing such as gender-neutral words and accurate vocabulary. Please select from the following examples the one that violates these principles. 
A、Using plural third-person pronouns (they, their, them, theirs) when the gender is unspecified rather than singular third-person pronouns (he/she, his/her, him, hers)
B、Using words like retarded, stupid, ugly, lazy, skinny, fat, horrible/horribly, terrible/terribly, lovely
C、Using conjunctions and linking phrases to signal new sections instead of numbering sections of text.