The answer is c. 1˚.
The levels of protein structure describe the organization of a protein, starting from the smallest and most specific unit, to the largest and most complex. The four levels of protein structure are:
Primary structure: This level describes the linear sequence of amino acids in a protein.
Secondary structure: This level describes the regular, repeating patterns of the polypeptide backbone, such as the alpha helix or beta sheet.
Tertiary structure: This level describes the three-dimensional shape of a complete, single protein molecule, including the spatial relationships of all its atoms.
Quaternary structure: This level describes the organization of multiple protein molecules into a functional, multi-subunit complex.
Therefore, the spatial location of every atom in a protein is described by its tertiary structure, or level 3.