According to the law of superposition, the bottom rock layer is the oldest youngest thinnest thickest

oldest

Explanation:

The Earth's crust, or Lithosphere, is the Earth's solid crust, its outermost, thinner, and consolidated layer, essentially made up of rocks. The rocks are formed by a set of minerals. In them we can find glass, salt, among others.

The rocks that originate in very deep areas of the earth's crust, and their ages are, in general, very old and more complex, while the more superficial layers have younger and less complex rocks.

x would be the most and the least would be y because there are more fruit   and seeds than flock z has insects