Un......est une personne qui travaillc a la boulangerie.

The sentence "Un......est une personne qui travaille à la boulangerie" translates to "A......is a person who works at the bakery" in English. To determine the correct word that fits in the blank, we must understand the roles of each professional:

Épicier: This is a grocer, someone who works in or owns a grocery store. They sell various food items but do not specialize in baked goods or work at a bakery.

Poissonnier: This is a fishmonger, a person who sells fish and seafood. They typically work in a fish market or a section of a grocery store that specializes in seafood, not in a bakery.

Boulanger: This is a baker, a person who specializes in baking and works in a bakery. A baker is responsible for making bread, pastries, and other baked goods. This role fits the description of someone working at a bakery perfectly.

Boucher: This is a butcher, an individual who prepares and sells meat. Butchers usually work in butcher shops or meat sections of supermarkets and do not work specifically at a bakery.

The correct answer is Boulanger, as they are the ones who work in a bakery. The term "boulangerie" directly translates to "bakery" in English. Thus, a "boulanger" is a person who works at a "boulangerie".