A fragment differs from a complete sentence because fragments do not express a complete idea or include both a subject and a verb that are necessary for a sentence, instead fragments tend to include only a subject or only a verb along with other words that complete them. In the case of "Scurried across the field" this item is a fragment (F) because it contains the main verb "scurried" that means to rush along with other words that complete the meaning of the verb "across the field" but it does not contain a subject or specifies who or what was hurrying.
Repetition shows to the reader what the author wants them to take away from the reading. If something is being repeated it is to put emphasis on the topic
