Main topic (Dewey)

No one doubts, theoretically, the importance of fostering in school good habits of thinking. Thinking not connected with increase of efficiency in action has something the matter with it. And skill obtained apart from thinking is not connected with any sense of the purposes for which it is to be used. It consequently leaves the students at the mercy of their routine habits and of the authoritative control of others who know what they are about and who are unscrupulous as to their means of achievement. And information severed from thoughtful action is dead, a mind-crushing load. Since it simulates knowledge and thereby develops the poison of conceit, it is a most powerful obstacle to further growth in the grace of intelligence. The sole direct path to enduring improvement in the methods of instruction and learning consists in centering upon the conditions which exact, promote, and test thinking. Thinking is the method of intelligent learning, of learning that employs and rewards mind.

Q: Which of the following is the major topic of the passage?

(A) Importance of good training in thinking for students

(B) Importance of acquiring information through thinking

(C) Importance of intelligence to find purposes in life

(D) Importance of habit-formation through methodical thinking

I think the answer is (D), but I'm not sure.

Please help me. Thanks a lot.