Details of the structures of three atoms, X, Y and Z, are given below. X: proton number $1$, nucleon number $1$ Y: proton number $1$, nucleon number $2$ Z: proton number $1$, nucleon number $3$ Which statements about atoms X, Y and Z are true?
- A1, 2 and 4
- B1 and 2 only
- C3 and 4
- D3 only