A certain radionuclide is used to diagnose lymphoma. An atom of this radionuclide contains 31 protons and 36 neutrons. Which statement is correct about the radionuclide?
A
The atomic number is 31, the mass number is 67, and its symbol is .
B
The atomic number is 31, the mass number is 67, and its symbol is .
C
The atomic number is 67, the mass number is 31, and its symbol is .
D
The atomic number is 67, the mass number is 31, and its symbol is .