Select the single word that best substitutes for the given phrase:

A person who draws or produces maps

The correct option is Cartographer.

Explanation:
Let us analyze the definitions of all the given options to find the correct single-word substitution for the phrase "A person who draws or produces maps":

1. Cartographer: Refers to a person who creates, draws, or produces maps and charts. Therefore, this is the correct substitute for the given phrase.

2. Astronomer: Refers to a scientist or scholar who studies celestial objects such as stars, planets, comets, and galaxies.

3. Sculptor: Refers to an artist who creates three-dimensional art objects or figures by carving, modeling, or casting materials like stone, clay, metal, or wood.

4. Calligrapher: Refers to a person skilled in the art of fine, decorative handwriting or lettering.

Thus, the single word that best substitutes the given phrase is Cartographer.