Formal language is language that one would use when speaking to someone of great importance or rank.
<em>Examples:</em>
<em>The queen, president, or other world leader</em>
You would not use slang while speaking or writing in formal language. Slang should only be used when speaking to close friends or family if you are speaking in a comfortable non-formal way. :)
Answer:
A.The Germans now had to rely on radio transmissions from their powerful wireless station at Nauen, a few miles from Berlin.
Explanation:
Cabled message could also be ciphered. The British knowing what the Germans would have to do doesn't mean they wouldn't or couldn't do it. They started sending wireless messages, but why? You can find the clear answer to that in the first option. Since they had to rely on radio transmissions, it means they had no other option.