A 28-year-old woman presents to the emergency department with a recent episode of coughing up some blood, frequent nosebleeds, and now decreased urine output. On physical examination, a nasal mucosa ulcer is seen on inspection and the remainder of the examination is normal. Her urinalysis is positive for protein and red cells consistent with a GN. The CXR shows two
cavitary lesions and her serology is positive for antineutrophil cytoplasmic antibodies (ANCA). Which of the following is the most likely diagnosis?