This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Body composition and Acid base Balance, Subject name: Pediatrics
What is the name of this test to be done before drawing an aerial blood gas sample: 
Select and explain. 
A. Virchow test, B. Water hammer test, C. Allen test, D. Trendelenburg test
C: Allen test
Answer: C: Allen test 
Explanation: Allen's test: to assess the aerial blood supply of the hand A - Both radial & ulnar aery are occluded; B - Ulnar aery kept occluded, Radial aery released Water hammer test- to detect water hammer pulse in aoic regurgitation Trendelenburg test- to detect weakness of hip abductors