This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorder of Metabolism & Connective Tissue, Subject name: Medicine
What is the diagnosis in this patient with abdominal pain? 
Select and explain. 
A. Amyloidosis, B. Familial Mediterranean fever, C. Lead poisoning, D. Leukemia
C: Lead poisoning
Answer: C: Lead poisoning 
Explanation: Answer C. Lead poisoningThe blue lines evident on the gums are Burton's lines, which can be present in patients with lead poisoning. The diagnosis of occupational lead poisoning was confirmed by an elevated serum lead level. The patient recovered following chelation therapy.