Sarah is likely experiencing elements of sex trafficking, although we don't know for certain. There are signs of action (recruitment) and means (abuse of power, force, coercion, deception), but Sarah has not yet shared details that would confirm purpose. Based on the fact that Sarah's boyfriend is forcing them to do "favours" for "nasty men" and she is returning withdrawn and covered in bruises, it is likely that these men are expecting Sarah to engage in sexual activities with them and she does not want to.
Sarah has not shown any signs of harm indicating the purpose of forced labour, tied to a workplace or employment. Try another option!
Mixed-type trafficking is most often comprised of simultaneous sex trafficking and labour trafficking. Sarah has shown signs of probable sex trafficking, although no signs of labour trafficking, so Sarah is more likely experiencing sex trafficking.

Sarah Soaring Eagle

Action, means, purpose