The answer would be c because a surface wave travels between two different materials, like air and water.
Answer:
In short, there are four types of natural silk produced around the world: Mulberry silk, Eri silk, Tasar silk and Muga silk. Mulberry silk contributes around as much as 90% of silk production, with the mulberry silkworm generally being regarded as the most important.
The stratosphere is the layer above the troposphere
magnetic materials will produce magnetic field near it
All magnets are made up of small magnet type atoms which are known as domains
These all atoms will align itself so that they all produce strong magnetic field along the axis
this magnetic field will become more strong as more number of atoms are aligned.
Now if we break the magnet into small piece then the magnetic field strength will start decreasing and at the end when only one atom will remain then the magnetic field strength will reduce to the field of one atom only.
