An angler experiences a glare of light coming from the water's surface. which type of glasses should she wear to minimize the glare?

He should wear polarizing sunglasses.

The glare is reflected light.  Reflected light is always substantially polarized.
He can cut the glare almost completely, but in order to do that, he'll need to
rotate his glasses until the polarization of the lenses is perpendicular to the
polarization of the glare. 

(I've never understood how you're supposed to do that.)