By the early 20th century, britain had built the world's most respected navy because

it needed to protect its vast overseas empire

Explanation:

From the late 17th to the mid-20th century, Britain's navy was the most powerful navy in the world, playing a key role in establishing the British Empire as the dominant world power. Great Britain invested heavily in naval force as a way to protect and maintain the supremacy of its vast overseas empire

the answer is d trust me

yes.

explanation:

because it let the japanese know who had the upper hand in the war.