Molal concentration of a solution is: a) Number of moles of equivalents of the dissolved substance in 1 dm 3 of a solution; b) Number of moles of the dissolved substance in 1 dm 3 of a solution; c) Number of moles of the dissolved substance in 1 dm 3 of the solvent; d) Number of moles of the dissolved substance in 1 kg of a solution; e) Number of moles of the dissolved substance in 1 kg of the solvent