Since a predicate adjective is the first adjective found after a linking verb (in this case 'seemed'), the correct answer is 'docile'.
Well, there are three types. Logos, pathos and ethos. Since a.(emotional or passionate statements) is mostly connected to pathos which makes a deep connection with the audience or reader, I'd say (a.) is the answer.
The main difference between the two writing is that Carson is concerned about the destruction of the entire environment, while Muir is only concerned about a certain part of the environment. John Muirs present evidence to persuade and encourage the readers to rescue the Sequoia meanwhile Rachel Carson shows a fictional story of what life would become if we do not save the environment.