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
Penny test is the quality assurance test to detect 
Select and explain. 
A. Fixer depletion, B. Unsafe illumination, C. Machine malfunction, D. Contaminated solution
B: Unsafe illumination
Answer: B: Unsafe illumination 
Explanation: None