I believe it to show some source of burning or chaos,sorry if this did not help
O heavy lightness! serious vanity!
O brawling love! O loving hate!
Feather of lead, bright smoke, cold fire, sick health! Still-waking sleep,
All of the above are oxymorons. An oxymoron is simply something that is a contradiction to itself. Feathers are light, but here they call them lead which implies they are heavy. And when does love hate?
I would say D, as it would allow the reader to understand the comparison being made
