If in a certain code language, 'oka peru' means 'fine cloth' ; 'meta lisa' means 'clear water' and 'dona lisa peru' means 'fine clear weather' , which word in that language means 'weather' ?

Answer: D. dona

In the first and third statements, the common code word is 'peru' and the common word is 'fine'.
So, 'peru' means 'fine'.