First, we need to know that:
The beta particle is: ₋₁⁰e⁻
helium-3 is: ₂³ He
the result of the sum of the atomic numbers and the sum of mass on the reactant side must be equal to the sum of the atomic numbers and the sum of mass on the product side.
So:
₁³ H ---> ₂³ He + ₋₁⁰e⁻ + v
Answer: alternative "b" ₁³ H ---> ₂³ He + ₋₁⁰e⁻ + v