Answer:
cold wave - a feeling of cold air
or a wave of water that is cold
or an emotional wave of sadness or gloomy
a fair day - a nice day
a day which had equal balance
a fine box - a good sturdy box - or a thin box
Compare, because that shows what is the same about them.
The answer is letter A. A business letter is a letter written in formal dialect, typically utilized when composing starting with one business association then onto the next, or for correspondence between such associations and their clients, customers and other outside gatherings.
The Germans would then find a different way of transmitting their messages.