The answer is A: a voyage.
In this poem, Emily Dickinson is comparing reading to a voyage, to travelling, by making it seem that reading is like embarking a strong and powerful vessel (the frigate) towards unknown places; or like riding a beautiful horse (the coursers) across a lovely field (poetry); and all of this without any cost or harm to the reader (anyone can read and embark on this wonderful trip).
The first sentence is complete, it is a sentence that can stand alone. The second one however, is NOT a complete thought. The second sentence needs more information to be a complete sentence. For example we could right.. Although early American writers were mostly men, women had their fair share of writing. So, all that being said, it is the second sentence. :)
Answer:
The town is far away
The california is big
The power of a grizzy bear is too much
The water is flowing towards the shop