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
A 15 year old male patient complains of pain in the lower back tooth. History of frequent snacking in between meals.
Intra-oral examination reveals occlusal caries with 16 and 36, proximal caries between 26 and 27 and grossly carious 46.
Which of the following must be used while taking a radiograph for this patient? 
Select and explain. 
A. Round collimator, B. Rectangular collimator, C. Short pointed aiming tubes, D. Short source-to-skin distance
B: Rectangular collimator
Answer: B: Rectangular collimator 
Explanation: None