Why? Because a. lazilier and d. laziliest are grammatically incorrect words, therefore not correct. B. most lazy is grammatically correct but it does not fit here because the sentence compares two things (so you need a comparative "more"), while the superlative "most" requires at least three things to be compared.
Both examples come from the Bible. The first comes from the Old Testament and the second from the New. You have to be a little knowledgeable of the Bible to catch on to either one of them (or be good with Google).