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: Pathology
Senile cardiac amyloidosis associated protein is ? 
Select and explain. 
A. Transthyretin, B. ANP, C. Beta 2 microglobin, D. Gelsolin
A: Transthyretin
Answer: A: Transthyretin 
Explanation: Ans. is 'a' i.e., Transthyretin