Problem: In older adult patient presents with vague abdominal discomfort and unintentional weight loss. Endoscopy reveals a malignant lesion in the stomach. Biopsy results show infiltrating, mostly individual tumor cells surrounded by dense fibrosis. What type of gastric cancer is most likely in this case? Group of answer choices Gastrointestinal stromal tumor (GIST) Carcinoid tumor Lymphoma Adenocarcinoma, diffuse type