In the decay sequence, 92²³⁸U → −x₁⁹₀²³⁴Th → −x₂⁹₁²³⁴Pa → −x₃²₃⁴Z → −x₄⁹₀²³⁰Th, x₁, x₂, x₃ and x₄ are particle/radiation emitted by the respective isotopes. The correct option(s) is (are)

Correct option is D.
Z is an isotope of uranium
⁹₂²³⁸U → −₂⁴He⁹₀²³⁴Th → −₋₁e⁹₁²³⁴Pa → −₋₁e⁹₂²³⁴Z → −₂⁴He⁹₀²³⁰Th
x₁ = α (since positively charged, so will be attracted by negative plate).
x₂ = β⁻ (negatively charged and attracted by positive plate)
x₃ = β⁻ (negatively charged and attracted by positive plate)
x₄ = α (since positively charged, so will be attracted by negative plate).
U and Z have the same atomic number so they are isotopes.