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
Beck's triad of cardic tamponade includesa) Hypotensionb) Neck vein distensionc) Silent heartd) Tachycardia 
Select and explain. 
A. acd, B. abd, C. abc, D. ab
C: abc
Answer: C: abc 
Explanation: None