Which One of the Following Students Is Exhibiting an Externalizing

Which one of the following students is exhibiting an externalizing behavior?

A) Tanya, who weighs 93 pounds but has stopped eating lunch and has cut back on other meals because she thinks she's too fat
B) Roberto, who has been overindulging in alcohol and making frequent comments about killing himself
C) Natasha, who has been unable to sleep through the night for months because she cannot stop worrying about her life
D) Peter, who has been stealing small items from his classmates' desks and publicly accusing others of taking them