Identifying Social Anxiety Disorder

Lucy is a college student who has been increasingly experiencing overwhelming anxiety about attending social events. Even the thought of going to a party or a gathering with peers makes her physically uneasy. She finds herself avoiding these situations more and more, feeling an intense fear that something terrible will happen if she goes. Lucy's anxiety has started to impact her academic performance and her social life. Based on this scenario, which of the following diagnoses is most likely applicable to Lucy's condition?