Answer:
D
Step-by-step explanation:
The goal in this set up is to make sure all units cancel each other.
Since we need to go from grams to atoms, our final unit should be atoms.
Using method of elimination, let's see why other options are wrong.
A - Although 'g' is cancelled out, we are left with moles^2 / atoms
B - Although 'g' is cancelled out, we are left with moles^2 / atoms
C - Although 'mol' is cancelled out, we are left with g^2 / atoms