Which of the following best defines salinity? A. the grams of water in 1 g of salt B. the grams of salt in 1 kg of water C. the grams of salt in 1 g of water D. the grams of water in 1 kg of salt

First of all, this question should not be categorized in "Geography". Second, if you know what salinity means, it is the concentration [M] of salt in water expressed in the units mg/L or ppm. Hence the correct answer would be B