<span>The correct answer is
(4). Natural resources discovered under the North Sea in 1959. that became
major products in the United Kingdom are oil and natural gas. The exploitation
began in 1971. Through tankers, and later by pipeline. The largest platforms are
Ekofiks oil field, Statfjord oil field and Troll gas field.</span>
The correct answer is Germany declared unrestricted submarine warfare against all ships.
What this means is that Germany claimed control of the seas and oceans and if anyone opposed it they would attack it with their submarines. The US joined the war 2 months later.
The answer is definitely A.