Assuming ideal conditions, which statement is true of the following samples of gases?

16g of O2
14g of N2
8g of CH4
1g of H2

a) They all have the same density at the same temperature and pressure.
b) They all have the same volume at the same temperature and pressure.
c) They are listed in order of increasing number of particles.
d) They are listed in order of decreasing number of moles.