'Baffle' is a verb which means 'to perplex, to confuse, to restrain or to frustrate'. Option D - 'Frustrate' is a verb which means 'to annoy, to infuriate or to irritate', which conveys a similar meaning as of the given word 'Baffle'.
On the other hand, Option A - 'Insult' is a verb which means 'to defame, to abuse or to malign', Option B - 'Defame' is a verb which means 'to insult, to discredit or to tarnish', Option C - 'Hunger' as a noun means 'need for food' and as a verb means 'to have a strong desire or craving', none of which convey similar meanings as of the given word.
Therefore, the most appropriate synonym for the given word 'Baffle' is D - Frustrate.