This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology, Subject name: Medicine
An industrial worker presents with blue lines on gums and tremors. What is the most probable diagnosis? 
Select and explain. 
A. Arsenic poisoning, B. Lead, C. Mercury, D. Carbon monoxide
B: Lead
Answer: B: Lead 
Explanation: Ref: Harrison's Principles of Internal Medicine, 18th edition, chapter 49Explanation:Lead poisoning-Source-batteries, lead paints, plumbing, lead pipes.Abdominal pain, anemia with basophilic stippling, anorexia,Headache, arthralgia, myalgia, tremorsLead line (Grey blue line) at the gingival-teeth border (Burton sign)Wrist drop. cogni t i ve dee 1 i neHigh blood protoporphyrin levelTreatment-DTfSA (succimer), CuEDTA. dimercaproArsenic poisoning-Vomiting, diarrhea, abdominal pain, coma, seizuresGarlicky breath odor, hyperkeratosisMeefs lines- transverse white striae on finger nailsDistal weakness, radio-opaque on abdominal X rayECG- Prolonged QRS. QT & ST depression. T flatteningTreatment: Dimercaprol. oral succimerMercury poisoningAcute inhalation - Pneumonitis, ARDSAcute ingestion - gastroenteritis, ARF. hypertension, tachycardia, cardiovascular collapseChronic - CNS symtoms, renal failureintentional tremor, mercurial erythrism. delirium, memory loss- 'mad as a hatter *Children- acrodynia. pink diseaseTreatment- Dimercaprol. DMSA, penicillamine. Cadmium poisoning-Acute inhalation- pneumonitis. ARDSAcute ingestion- gastroenteritisChronic exposure- anosmia, yellow teeth, emphysema, anemia, CRF, osteomalaciaTreatment- supportive