Volcanic activity , earthquakes , tsunamis.
the correct answer is bamboo and silk
Chinese have been the world sole producer of silk for several centuries, a commodity that often caused a balance of trade deficit between the country and the rest of the world. the secret of silk making was also protected with royal decree for a long time, which makes it a popular material for making music instrument. Bamboo is often preferred for its hollow inside.
No because some angles may be different.
Sorry i just did this for points
