The themes is plural hence we need "are"
A and B out.
C - they encompass and occasionally deals. (They deal not deals)
E- Is wordy, also its not certian if "They" Refers to poetry or to the themes, also "they encompass much of the human condition" is set off with commas indiccating that it is a non essential clause, making the sentence rubbish.
D is Clear - encompassing much of the human condition while occasionally is a participal phrase that modfies correctly the subject "The themes"