Invasion literature is still popular becuase it:

The invasion literature is a literary genre that was recognize in a short story about a fictional invasion from Germany to England, the novel was published in 1871, this novels deal with fears that are still relevant, with the distress and anxiety of an invasion by an external power. The answer is B.

hello!

i don't seem to see any options! could you tell me what they are? !

  this riddles' answer is library.

  the "leaves" are a reference to the books' pages that the library contains; the branches are a network of libraries that connect multiple libraries' collections, resources, and items in a system of a common database, integrating them; the branches' organization are a useful management tool for coordinating the multiple collections many libraries have.