I was referring to "Plants and viruses are also pretty smart." that implied that killing plants is not OK. Clearly humans have to kill living creatures to surv

I was referring to "Plants and viruses are also pretty smart." that implied that killing plants is not OK. Clearly humans have to kill living creatures to survive, but a moral problem only raises when one has a choice. And we do have a choice between eating, say, a ton of grains or feeding a cow 10 tonn of grass and then killing the cow.