What was the main reason imperial nations built large naval forces? to initiate sea-based attacks on other nations to support nearby merchants to protect their economic interests to resist attacks on their harbors

C. to protect their economic interests

Explanation:

Naval power of country determined the economic strength of nation. Portuguese is the superior in naval power in 14th century then Spain and Britain are rivalries in ocean. They capture the land and constructed colonies in different regions for their own country’s economic wealth. Superior naval powers determines the result of the two world wars. In modern world, Naval power protect the own country economic interests via trade. Longest sea shore countries are much wealthier than landlocked countries in economically and politically.

polar areas, such as antarctica or the south pole.