I wonder which solution is better, is there really a better solution or maybe it depends on context?
It depends on the context. I assume this might be coupled with related info (publishing date, author, retweets etc.) If that's the case option A and B are less direct as there will be more to read.
The speech bubble is a well established symbol for comments which makes option C and D more direct than E. When it comes to deciding between C and D it's trickier and again it's down to context. For instance, if there is other related info that is on the same horizontal line, e.g. 20 [comment icon] 159 [retweets], it can be interpreted that there are 159 comments.
I'd go with C as it's most direct and least likely to be misinterpreted.