Answer:
Four layers
Explanation:
There are total four layers of Neptune. These four layers are - core, mantle, atmosphere, and upper atmosphere
a)	Core – It is made up of rock and ice
b)	Mantle – It is made up of water, ammonia, and methane ices.  
c)	Atmosphere – It is made up of hydrogen, helium, and methane gas
d)	Upper Atmosphere – It has trace amount of helium