What Is the Coefficient for H₂ When the Equation ___ $\rightarrow$

What is the coefficient for H₂ when the equation ___ Ba + ___ H₃AsO₄ $\rightarrow$ __ H₂ + ___ Ba₃(AsO₄) ₂ is properly balanced?

A) 1
B) 3
C) 5
D) 2
E) 6