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: Medicine
Decreased Radio iodine uptake is/are seen in -a) Toxic multinodular goiterb) Grave's diseasec) Subacute thyroiditisd) Factitious thyroiditis 
Select and explain. 
A. ac, B. ad, C. cd, D. bd
C: cd
Answer: C: cd 
Explanation: None