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
Presence of 1 up quark + 2 down quarks suggests the following: 
Select and explain. 
A. Proton, B. Neutron, C. Electron, D. Positron
B: Neutron
Answer: B: Neutron 
Explanation: None