The correct answer is option (D):
nothing but dishonest
The correct answer is "nothing but dishonest." Let's break down why and why the other options are incorrect.
The original sentence expresses that the person is *only* or *merely* a dishonest person. The phrase "nothing else but" or a similar construction is used to limit the description to a single, defining characteristic.
* "Nothing but" is the most concise and grammatically correct way to convey this meaning. It means "only" or "solely". So, "He is nothing but dishonest" accurately states that dishonesty is the only thing he is.
Now let's look at why the other options are wrong:
* "Nothing else lest a dishonest": "Lest" introduces a fear or possibility of something happening. It doesn't fit the context of defining the person's character. This phrase structure is grammatically incorrect in this scenario.
* "Nothing else than a dishonest": While this is closer, the repetition of "else" and the article "a" before "dishonest" is redundant. It sounds awkward and less direct than "nothing but."
* "Nothing else except a dishonest": "Except" means "with the exclusion of". This implies that the person is *not* only dishonest, but has other characteristics as well, while this sentence should describe the defining character. The sentence is then made incorrect as it changes the initial meaning.