Answer:
Over.
Step-by-step explanation:
Prepositions are the words that tell us the position of the nouns. In other words, they tell us the relation of the nouns and pronouns with the other words in the sentence.
In the given sentence, "eagle" is the noun, "majestic" is the adjective, the verb is "soaring" and the preposition is "over". It tells us the position of the eagle, the movement of the eagle.
Thus, the correct answer is "over".