And what is a mole? It is a counting number like 10, or 12, or 100. One mole of stuff specifies 6.022×1023 individual items of that stuff.
Why should we use such an absurdly large number? It happens that if I have 6.022×1023 individual 12C atoms, I have a mass of 12.00⋅g precisely. The mole is thus the link between the (sub)micro world of atoms and molecules, which we can't see, with the macro world of grams, and litres, and kilograms, which we can measure in a lab.
So we have got 6.022×1023 CO2 molecules, and 22.4⋅L of CO2 molecules at STP, and 0.44⋅g of CO2. In fact, 6.022×1023 CO2 molecules, and 22.4⋅L of CO2 molecules at STP, have the same number of molecules by definition (and have a mass of 44⋅g), and thus the same number of atoms.
This is not a good multiple choice question, because 2 answers are valid.
