B. My favorite of all the subjects.
This is a sentence fragment because it's not telling you the object of the sentence, or what the subject is acting upon.
Answer:
A mast
Explanation:A mast is a pole that rises vertically from a ship and supports the sails. Really big sailboats have more than one mast. A mast is also another name for flagpole.
Either Mark or his students were on the ferry boat.