Why does churchill believe an invasion of british soil is not likely to occur in the near future?
a.) because french forces were pushing the germans back into poland
b.) because the enemy did not have a powerful enough air force
c.) because american ships were blocking entrance to the english channel
d.) because the enemy could not keep its troops supplied from such a great distance

The correct answer is D. Because the enemy could not keep its troops supplied from such a great distance. Churchill supports this view in his speech "Their Finest Hour".

d.) because the enemy could not keep its troops supplied from such a great distance

Explanation:

In his discourse, Winston Churchill, PM of Britain amid WWII, delivers the British to guarantee them that they are protected, and that the German armed force would have it extremely hard so as to attack British, since they'd discover an ocean topped off with mines, air bombings, and the British armed force before they could even land a foot on shore and face the British armed force. They had the sea heavily guarded.

answer: do

the 'italicized phrase' is a noun clause that is used as a direct object.