The thesis statement could be based off the 95 theses that Martin posted on the Catholic church's door on 1517. He did not agree to some Catholic ways. He had found out that the pope had used the 'offerings' of the church to treat himself. He also felt that God wanted for believers to seek repentance and not faith alone.
This is a perfect example of a thesis statement.
So with this knowledge, we know the correct answer would be B) A statement of the position you will attempt to prove.
Hope this helps!