Select the correct text in the passage.
Which two sentences best highlight the idea that the theremin is unlike most conventional musical instruments?
The Theremin

The theremin is one of the earliest electronic musical instruments and is distinct as it is played without any form of physical contact between the musician and the instrument. The Russian physicist Leon Theremin invented this instrument in 1920, and he exhibited his innovation all over the world. The instrument has an unusual appearance and consists of two metal antennas. The upright antenna controls the pitch, and the loop antenna controls the volume. The musician moves his hands over the antennas to create electrical signals, which are magnified through the instrument and relayed to the loudspeaker. The theremin sounds ethereal and transports the listener to another world.

The instrument became very popular in the 1930s, but it soon faded into obscurity due to a lack of interest. However, it was revived in the 1990s, and since then, it has featured in the soundtracks of many movies. Many composers have created musical symphonies that showcase the unique notes of the theremin. It is one of the most difficult instruments to master because even a proficient player requires a lot of practice to control the intonation of the musical notes. Today, many enthusiasts also build theremins as a hobby using building kits available online.