Which of the following levels of protein organization shows the complete 3d arrangement of the polypeptide chain

Proteins are the macromolecules made of hundreds of amino acids. Proteins are most varied class of biological molecules and show the greatest variety of structures. Many have detailed three-dimensional folding patterns that result in a compact form, but others do not fold up at all and they are in random conformations. The function of proteins depends on their structure.

The secondary structure of protein fold together to form the 3D arrangement of a polypeptide chain that results into Tertiary structure which is a functional protein.    

X: plant material

Y: meat

Explanation:

Just look at the molars: One is obviously for eating meat, as the jaws in the front are sharp and can easily shred meat. One is for chewing plants, as it's molars are flat.