**Core Concept**
The spatial arrangement of atoms within a molecule is a critical concept in biochemistry. It refers to the three-dimensional structure of a molecule, which plays a crucial role in determining its chemical and biological properties.

**Why the Correct Answer is Right**
The correct term for the spatial relationship of every atom in a molecule is indeed "conformation." Conformation refers to the specific arrangement of atoms in space, which can vary depending on the molecule's functional groups, bond angles, and torsional angles. This concept is essential in understanding how molecules interact with each other and their surroundings. In biochemistry, conformational changes can significantly impact enzyme activity, protein function, and even disease mechanisms.

**Why Each Wrong Option is Incorrect**
**Option B:** Configuration refers to the arrangement of atoms or groups of atoms in a molecule, but it specifically refers to the spatial arrangement of atoms in a particular stereocenter (a carbon atom bonded to four different groups). While related to conformation, configuration is a more specific term that focuses on stereocenters.

**Option C:** Both of the above is incorrect because while conformation and configuration are related, they are not interchangeable terms.

**Option D:** None of the above is incorrect because, as explained, conformation is indeed the correct term for the spatial relationship of every atom in a molecule.

**Clinical Pearl / High-Yield Fact**
When considering the spatial arrangement of atoms in a molecule, remember that even small changes in conformation can have significant effects on molecular interactions and biological activity. This concept is crucial in understanding the mechanisms of action of various drugs and enzymes.

**✓ Correct Answer: A. Conformation**