Population “b” was killed more quickly than population “a”. Because the two populations started with the same number of organisms and they are the same kind of organism, population “b” must have been subjected to more destructive or toxic conditions than population “a”. These could have been a higher temperature, greater concentration of germicide, or greater intensity of destructive radiation. Populations “a” and “c” are dying at the same rate so they are under equally toxic conditions. The difference is that population “c” started with a smaller number of organisms and was reduced to a zero cell number in a shorter time period.