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: Surgery
Metastasis in thyroid gland come most commonly from carcinoma of 
Select and explain. 
A. Testis, B. Prostate, C. Breast, D. Lungs
C: Breast
Answer: C: Breast 
Explanation: The above-mentioned book is solely dedicated to surgery and diseases of thyroid & parathyroid gland.

It writes -
"Metastatic disease to the thyroid may occur as a consequence of direct extension from upper aerodigestive malignancies, i.e., squamous cell Ca, or by hematogenous spread. Evidence at autopsy has demonstrated upto 20% of patients exhibiting distant metastasis to the thyroid gland from breast, lung, kidney, & melanoma skin most commonly."