Ibet you have watched astronauts in the space station on television or on your computer. we see them; we hear them speak. how are the voices of astronauts transmitted back to earth? a) sound waves b) transverse waves c) mechanical waves d) longitudinal waves

The only way to send information back and forth is to use radio waves. Just like a radio station broadcasts a signal which you can listen to using a radio, astronauts and people on Earth can broadcast information back and forth to each other.
Radio waves are transverse waves.

The truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey