The Dobson unit (DU) is used as a metric for gauging the extent or thickness of the Earth's atmospheric layer.
Therefore, The correct option is (D): Dobson units
List I | List II | ||
---|---|---|---|
A | Mesozoic Era | I | Lower invertebrates |
B | Proterozoic Era | II | Fish & Amphibia |
C | Cenozoic Era | III | Birds & Reptiles |
D | Paleozoic Era | IV | Mammals |