To determine which is the correct answer, we convert the mass of the compounds into units of particles of the compound. We use the molar masses and the Avogadro's number. We do as follows:
76.9 g I2 (1 mol / 253.81 g) (6.022x10^23 particles / 1 mol ) = 1.82x10^23
79.9 g Br2 (1 mol / 159.81 g)(6.022x10^23 particles / 1 mol ) = 3.011x10^23
6 g C (1 mol / 12 g)(6.022x10^23 particles / 1 mol ) = 3.011x10^23
13.01 g CH4 ( 1 mol / 16.04 g )(6.022x10^23 particles / 1 mol ) = 4.88x10^23 particles
Therefore, the answers are Br2 and C.