[Majestic Mansion] Akira Inherited Her Family's Mansion in the Mountains

[Majestic Mansion] Akira inherited her family's mansion in the mountains from her grandmother. Akira lives in the mansion with her sister, Kitara. Their grandmother's will states that Akira inherits the mansion so long as she does not alter the exterior, and if she did, the mansion would belong to the historical society. The will also states that Kitara can live in the mansion for the rest of her life. Akira decides to place an addition on the mansion, and she knocks down one side of the building to add a modern-style wing. Akira's sister, Kitara, is upset that their grandmother left the mansion to Akira, and, when she discovers the construction, she tells Akira that Akira is no longer the owner of the mansion.
-Who is the rightful owner of the mansion?

A) The local historical society
B) Akira, because she has possession.
C) Akira's grandmother.
D) Kitara.
E) Akira because she has a fee simple absolute interest.