  We argue that Raman study of Fe-pnictides is a way to unambiguously
distinguish between various superconducting gaps proposed for these materials.
We show that $A_{1g}$ Raman intensity has a true resonance peak below $2\Delta$
for extended s-wave superconducting gap, $\Delta(\mathbf{k}) = \Delta (\cos k_x
+ \cos k_y)/2$ in the folded Brillouin zone. No such peak emerges for a pure
s-wave gap, a d-wave gap, and another extended s-wave gap with
$\Delta(\mathbf{k}) = \Delta \cos{\frac{k_x}{2}} \cos{\frac{k_y}{2}}$ proposed
by several groups.
