2. Each word is coded with a letter. 253 means "books are old",546 means "man is old".by these two we can say that 5 means old.
253 means "books are old", and 378 means "buy good books", we can say that 3 means books.
253 means "books are old", we know meaning of 5 and 3, so we can "are" is coded as 2.
3. It is too easy. First see options. OMES***M.This part is common, in every option. Left part to code is ONS from RESPONSE.
In QUESTION, last ON is written as IC, S is written as E.
So, option C is correct answer here.