Explanation:

- The sentence reads, "Owing to his ill health, he retired from business."

- Let's analyze the underlined word "Owing":

- Option 1: Conjunction

- Conjunctions join words, phrases, or clauses. "Owing" does not do this here.

- Option 2: Preposition

- Prepositions show relationships between nouns or pronouns and other words. "Owing to" indicates a cause, which is a prepositional phrase.

- Option 3: Participle

- Participles are verb forms used as adjectives or to form verb tenses. "Owing" isn't functioning as an adjective here.

- Option 4: Conjunction

- This repeats Option 1. "Owing" still isn't a conjunction.

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