Alfred T. Mahan argued that to protect its trade, the United States must build up its

a. army
b. navy
c. labor unions
d. pioneer spirit

B?

Right! :-)

http://wiki.answers.com/Q/Why_did_alfred_t_mahan_and_henry_cabot_lodge_call_for_the_building_of_a_strong_us_navy

Yes, the correct answer is b. navy.

To arrive at this answer, we need to understand who Alfred T. Mahan was and what he argued for. Alfred Thayer Mahan was a prominent American naval officer, historian, and strategist in the late 19th century. He advocated for the importance of a strong navy as a means for the United States to protect its trade and secure its interests globally.

Mahan argued that a strong navy was crucial for protecting trade routes and ensuring the country's economic well-being. He believed that a powerful navy would enable the United States to project its influence and protect its commercial interests around the world. By controlling the seas, the United States would be able to secure its trade routes, protect its merchant vessels, and maintain access to valuable markets.

Therefore, the answer is b. navy, as Mahan argued that the United States must build up its navy to protect its trade.