The answer is
<span>Coordinating conjunctions connect words, phrases, and clauses. Coordinating conjunctions include: but, and, or.
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<span>The answer is letter D.
Rocket is the simple subject in the sentence above. Simple subjects are the most basic units in sentence constructions. A subject is a noun that talks about a person, place, thing, or idea. It tells us what the sentence going to be about and without it we cannot have a complete sentence that has sense. In the sentence above, the rocket is the subject of the sentence which is responsible for the effect of making space travel possible.<span>
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