Identify the part of speech of the underlined word: The boys ran round the tree

The underlined word is round, and the test to apply is whether it takes an object. In "The boys ran round the tree", it links the action of running to the noun phrase "the tree" and shows where the running happened. A word that governs a noun or pronoun and shows its relation to the rest of the sentence is a preposition, so the answer is D.

Why the other options fail:

• Adjective: it would qualify a noun, as in "a round table". Here it qualifies nothing.
• Adverb: it would modify the verb and stand alone, as in "the boys ran round", meaning they ran in circles. Once "the tree" follows, it is governing a noun, which is a preposition's job.
• Noun: "round" is a noun in "a round of golf", but here it is not the subject, object or complement of anything.

Core concept: a word's part of speech depends on its function in the sentence, not on its spelling. This matters for precis and essay writing, where loose use of prepositions and adverbs changes meaning.

Trap: students see "round" describing motion and pick adverb. Check for an object first.