Correct Option is : (C) 18, 15, 16
Atomic Number = Number of Protons
Mass Number = Number of Protons + Number of Neutrons
Number of Electron = Atomic Number -(Number of Charges)
Therefore,
Number of Protons = 15
Number of Neutrons = 31 - 15 = 16
Number of Electrons = 15 - (-3) = 15 + 3 = 18
Hence , \(^{31} p^{3-} \) contains , 18 electrons , 15 protons and 16 neutrons.