Answer:
D) radio waves
Explanation:
Radio Waves -- The waves in the electromagnetic spectrum that have the longest wavelengths and lowest frequency are called radio waves. Radio waves are used to transmit information from the antenna of a broadcasting station to the antenna of your radio or TV.
Answer: The answer is 9 countries.
Explanation: Bulgaria, Croatia, Czech Republic, Denmark, Hungary, Poland, Romania, Sweden, and the United Kingdom (None of them use the euro)
In fertile mountain valleys.