Type effectivity:
Grass should be resistant against Light...period.
I mean if Grass is resistant to water, grass should also be resistant to lightÂ

Uhh... there is one problem mate...
Grass already is resistent to light LOOOOOOOOL. Well, its 100%... thats normal but i think thats okay. Doesnt really need 50% though, cuz intense light can burn grass xD
Look better next time

100% isnt resistant lolAnd intense water can kill plants too :-p
Is there any reason for light to be resistant to grass?
Is it, perhaps, because grass absorbs light?
I'll have you know that not all parts of the plant absorbs light.
True but I imagine not all parts of the plant absorb water either :-p