Answer:
The correct answer is D, farming.
Explanation:
The first option is wrong because although shipbuilding was an important economic activity, it was not more important than farming.
Option B is wrong because the Industrial Revolution had started only recently and there had not been enough time for the US to bring tools to improve manufacturing to an important degree.
Option C is wrong because it was an activity made almost only for subsistence.
Option D is right because farming was made not only for subsistence but also for an intern American market. Since the US was still changing its economy after being free from British colonial restrictions, farming was the main producer of goods.
