Both has the same molecule, CO2 molecule is 1 mole and NH3 molecule is 1 mole too.
Their atoms are different.
1 mole of (means 1 molecule) carbondioxide : 1 mole of O and 2 moles of C = 3 moles of atom (one mole of CO2 made by 3 moles of atom)
1 mole of (means one molecule) ammonia : 1 mole of N and 3 moles of H =4 moles of atom ( One mole of NH3 made by 4 moles of atom )
The answer is B.
sorry for my bad English btw, I tried to explain as far as I can.
Hope it helps!
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