Even when ultrasound suggests a fibroadenoma, a 50-year-old (outside the usual 15-35 range) needs tissue diagnosis. The lecture recommends core needle biopsy if there are suspicious features or older age. Core biopsy is also the standard diagnostic biopsy for breast masses. Observation (A) applies only to young women with small, non-suspicious lesions. FNA (B) is less informative, and an older textbook excerpt favouring FNA or excision is outweighed by the lecture.