Read the following passage , then choose the correct answer.

Music can move the soul. It can be a very strong influence. Some music can calm us down, but some music can make us wild! How does music affect us? Music is used in a variety of ways. It is used in the medical field as a source of research and as a sort of therapy as well. Music has been used as therapy for seizures , to lower blood pressure, treat mental illness, treat depression, aid in healing, treat stress and insomnia and premature infants. Musicologist Julius Portnoy found that it can change heart rates, increase or decrease blood pressure, effect energy levels, and digestion, positively or negatively, depending on the type of music. Calming music, such as classical music was found to have a very calming effect on the body, and cause the increase of endorphins, thirty minutes of such music was equal to the effect of a dose of valium. Both hemispheres of the brain are involved in processing music. The music in these studies is not the "lyrics", but the music itself, the melody, the tones, the tunes, the rhythm, the chords. Conversely music has also been documented to cause sickness. The right, or wrong music, rather, can be like a poison to the body. Studies have been done on plants where loud hard rock music, for instance, killed plants and soft classical music, make the plants grow faster. Music is very powerful, like a drug and can even be an addiction. According to Patty Hearst, a reseacher on music, it was documented that music was used in the aid of brainwashing some people. In the book,” Elevator Music” by Joseph Lanza, it was stated that certain types of music over prolonged periods in certain conditions were shown to cause seizures.

1. Which is the main idea of the text?