Which phrase is an example of an oxymoron in this passage?

Here's much to do with hate, but more with love.
Why then, O brawling love, O loving hate,
O anything of nothing first create!
O heavy lightness, serious vanity,
Misshapen chaos of well-seeming forms,
Feather of lead, bright smoke, cold fire, sick health
Still-waking sleep that is not what it is!

A) Here’s much to do with hate
B) Well-seeming forms
C) Sleep that is not what it is
D) Cold fire