The correct answer is C. 5 gram of molecule.
1 mole of any substance contains 6.022 x 10^23 molecules. The molar mass of carbon monoxide is 28.01 g/mol. Therefore, 1 mole of carbon monoxide contains 6.022 x 10^23 molecules of carbon monoxide.
In 6.02 x 10^24 CO molecules, there are 10 moles of CO molecules. The molar mass of oxygen is 16 g/mol. Therefore, 10 moles of CO molecules contain 160 g of oxygen.
Therefore, the number of g-molecule of oxygen in 6.02 x 10^24 CO molecules is 5.