I think c may be your anwser but im not too sure :/ srry if u get it wrong!
Carbon filtering is a method of filtering that uses a bed of activated carbon to remove contaminants and impurities, using chemical adsorption. ... Active charcoal carbon filters are most effective at removing chlorine, particles such as sediment, volatile organic compounds (VOCs), taste and odor from water.
1 kpa = 7.5 mm of Hg [Remember it or can be found on internet ]
So, 275 kpa = 7.5 x 275 = 2062.5 mm of Hg
One because Potassium is in the first column on the periodic table. Any element in the first column on the periodic table has one valence electron in their outer shell.
