Answer: A. Compressed.
Step-by-step explanation:
Flash Fiction is described as a short story that is can run from a few words to a maximum of 1,500. It is therefore a very short story. Regardless of it's length though, it still tries to include character development and a plot to make the story worthwhile.
For such a story to be able to do that, it needs to compress the details of the story so that it all fits. This is why flash fiction is said to be compressed.