The answer to this is letter C. You need to solve in order to get this answer. There are only two steps so you do not have to make a lot of effort to solve. The first step is to divide your grams and then divide by molar mass. This will become 118.082 grams divided by 39.1 grams. The answer will be 3.02 moles.
You are not done yet because you still have to do the second step. Change the moles to atoms by multiplying it with the Avogadros number. The equation will be 3.02 x 6. 02 x 10^23. You will get the answer for letter C which is 1.818 x 10^24 atoms. You can use the same formula when you are solving similar problems.
To change from grams to atoms requires TWO steps:
1st: change to moles: Take your grams and divide by molar mass.
118.082 g divided by 39.1 g = 3.02 moles
2nd: Change to atoms: Take your moles and multiply by Avogadros number:
3.02 x 6.02 x 10^23 = 1.818 x 10^24