Answer:
B is your answer :)
Explanation:
Both parts of that sentence could stand alone as there own sentence.
The correct answer is D.
The teacher clearly dislikes his students; he describes their work as slovenly and says that he is sick and tired of dealing with them.
He explains that he will not take the last of his energy and waste it on them, since they are so indifferent. While he does not like them, he does not yet hate them. He says if he were to give them the last of his energy, however, he would end up hating them. For now, though, he just dislikes them and waits for the bell.
