In a certain code language, 'sitting offers every' is coded

Solution

I: 'sitting offers every' is coded as 'rsa egb wsd'.
II: 'offers year lush' is coded as 'lks egb mla'.
III: 'century sitting lush' is coded as 'kxa rsa mla'.
From statement I and III, we conclude that 'sitting' is coded as 'rsa'.
From statement I and II, we conclude that 'offers' is coded as 'egb'.
From statement I alone, we conclude that 'every' is coded as 'wsd'.
From statement II and III, we conclude that 'lush' is coded as 'mla'.
From statement II alone, we conclude that 'year' is coded as 'lks'.
From statement III alone, we conclude that 'century' is coded as 'kxa'.
So, the code for 'century every year' is 'kxa wsd lks'.