I don't know what text you're talking about, but I believe the answer would be C. "fifteen designs"
A can be changed to "Memorial mission" or something.
B can be changed to "Pretty structure" or something.
D can be changed to " Available leasing area".
C will always need fifteen, as that's a prime word, it's needed to explain something. If you change that word, it'll change everything else.
Answer:
Probably the first one - it may create tension and will be exciting to read and maybe will become a hero in a fantastic way the reader will enjoy
(just an idea)
To refer to the first person narrator.