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
Disadvantages of grids are: 
Select and explain. 
A. Skin exposure of patient, B. Increase exposure time, C. Doesn't improve image, D. Overall density of radiograph is increased
B: Increase exposure time
Answer: B: Increase exposure time 
Explanation: None