The thickness of the ozone layer is quantified using the Dobson unit. Named in honor of Gordon Dobson, who pioneered early ozone measurement instruments, a Dobson Unit (DU) quantifies the total ozone within a vertical column of the Earth's atmosphere. Specifically, 1 Dobson Unit corresponds to a layer of ozone measuring 0.01 millimeters in thickness under standard temperature and pressure. Consequently, Dobson is the correct unit for ozone layer thickness measurement among the available choices.