Which part of speech shows the relationship of a noun to another word?

The correct choice highlights a key function in grammar. A preposition is a part of speech that connects a noun (or pronoun) to other words in a sentence, establishing a relationship between them. This relationship can indicate various aspects such as direction, location, time, or method. For instance, in the phrase "The book is on the table," the preposition "on" shows the spatial relationship between "book" and "table."

Utilizing prepositions allows for clarity and specificity in communication, as they help to build complex ideas by linking nouns and providing context to the actions or states described in a sentence. Understanding prepositions is fundamental for grasping how to articulate relationships in language effectively.