Chickens eat small rocks for what reason?
a) they lack teeth, so this aids with digestion.
b) they will eat anything that is put in front of them.
c) they are the only available source of minerals.
d) past cultures have used them to clear land.

a

Explanation:

As they forage, chickens naturally consume small pieces of rock, grit and/or gravel, and those pieces pass through their digestive system and lodge in their gizzard, where they chew up the seeds, grains, bugs, and grasses that they eat. The grit grinds their food the way molars grind our food

it's Z because X, W and Y is a vascular plant so it means that Z is not