No, the answer is c.
Work Step by Step
When you have two gases of different densities, the gas that is the least dense will tend to rise and the more dense gas will tend to sink. In the case of helium balloons, the two gases are Helium and Air. Air is made up mostly of Nitrogen (with some oxygen) so we compare the molar masses of Helium and Nitrogen to compare the densities. Helium has a molar mass of 2g/mol Nitrogen is N2 and has a molar mass of 28 g/mol Since helium is less dense, it will tend to rise. This is explained in choice c.