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: Radiology
The contrast in X-rays is dependent - 
Select and explain. 
A. Kvp, B. Mas, C. Duration of exposure, D. Distance between source and object
A: Kvp
Answer: A: Kvp 
Explanation: Kvp determines   →  Penetrating power of X-ray, contrast.
mAs determine   →  Number of X-ray photons, density of film (Blackening of film).