Answer:
I won't write 100 words for the answer but the theme is the process of becoming.
Bluebirds should have a round entrance hole measuring 1½" to 19/16" in diameter, or a 1⅜" x 2¼" vertical oval hole, or a 1⅛" to 13/16" horizontal slot entrance.
The answer would be C. Georg and Ulrich. Hope this helps!
Answer:
All of them is most likely a reason