This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Monitoring for Iodine levels is done by 
Select and explain. 
A. Urinary excretion of Iodine, B. TSH, T3 and T4 levels, C. Iodine level in soil, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None