Solubility of gas

The above left is a cylinder containing $1$ kg of water at $0$ °C. Then gases A and B nonreactive to each other are added. After enough time passes, as the picture on the right shows, the height $h$ is stabilized with partial pressures of both gases being $0.5$ atm. The solubilities of gases A and B at $0$ °C and $1$ atm are $2\times10^{-3} \text{ g/100 g of water},$ $4\times10^{-3} \text{ g/100 g of water},$ respectively. If the formula weight of B is twice as much as that of A and the mass of the piston is negligible, which of the following statements is/are correct?

a) The dissolved weight of gas B is twice as much as that of gas A.
b) The number of moles of gases A and B, when added initially, were not the same.
c) The molalities of gases A and B, after being dissolved in the water, are the same.