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
1upquarks + 2downquarks suggests the following: 
Select and explain. 
A. Proton., B. Neutron., C. Electron., D. Positron.
B: Neutron.
Answer: B: Neutron. 
Explanation: None