Answer: A. Our mission is to boldly go where no one has gone before.
When a word or phrase is placed between a particle and a to-infinitive, such grammatical construction is called a split infinitive. When there is an adverb between a “to” and a verb in a sentence, it becomes a split infinitive. Some examples are “to clearly see”, “to further develop”, “to more than double”. “Our mission is to boldly go where no one has gone before” has in it a split infinitive. The correct answer is option A