This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Radiology
A patient presents with a solitary pulmonary nodule (SPN) on X-ray. The best investigation to come to a diagnosis would be - 
Select and explain. 
A. MRI, B. CT scan, C. USG, D. Image guided biopsy
B: CT scan
Answer: B: CT scan 
Explanation: CT scan is the idol method to come to diagnosis of SPN