Select the option that can be used as a one-word substitute for the given group of words.
An open space usually rectangular and enclosed in a building

The correct answer is Quadrangle.

Explanation:

Let us analyze the meaning of the given words to find the correct one-word substitute:

1. Quadrangle: An open, four-sided space or courtyard, usually rectangular and enclosed by buildings (especially in schools or colleges). This directly matches the given definition.

2. Quadruped: An animal that has four feet (e.g., a dog or horse).

3. Quinton: A rare surname or a five-stringed musical instrument of the violin family.

4. Quintessential: Representing the most perfect or typical example of a quality or class.

Therefore, the word that best substitutes "An open space usually rectangular and enclosed in a building" is Quadrangle.