If the Average Rate of Formation of H₂(g) Is 3 $\rightarrow$

If the average rate of formation of H₂(g) is 3.90 (mol H₂) .L^-1.s^-1 for the reaction2PH₃(g) $\rightarrow$ 2P(g) + 3H₂(g) ,The unique average reaction rate is

A) 3.90 mol.L^-1.s^-1.
B) 1.30 mol.L^-1.s^-1.
C) 2.60 mol.L^-1.s^-1.
D) 7.80 mol.L^-1.s^-1.
E) 11.7 mol.L^-1.s^-1.