Rose received a letter full of love from her parents on her ______ birthday.
A:sixteen
B:sixteen's
C:sixteenth
D:sixteenths
①社会主义民主具有真实性
②我国促进各民族共同繁荣
③国家优先发展少数民族地区经济
④各民族共同繁荣是社会稳定的前提