Answer:
D
Explanation:
From each of the options, they're all radioactive decays and radioactive particles were emitted.
Option A is
²¹²₈₃Bi → ²¹²₈₄Po + ⁰₋₁e
This decay emitted an electron and it is also known as a beta (β) particle
Option B
²³⁹₉₃Np → ²³⁹₉₄Pu + β
This is also a beta β-particle decay and its similar to option A
Option c
⁶⁰₂₈Ni → ⁶⁰₂₈Ni + γ
This type of decay releases a particle called gamma particle hence the radioactive material undergo a gamma decay. Gamma emissions are characterized by zero charge and no change in the atomic number of the sample.
Option D
²³⁵₉₃Np → ²³¹₉₁Pa + α
This sample undergo an alpha particle decay and alpha particles are know to have a mass of helium atom (⁴₂He)
²³⁵₉₃Np decayed to become ²³¹₉₁Pa with a deficit of ⁴₂X and its known as a helium particle