*$___________ rubber is generally used for making 'O' rings used for vacuum sealings.?

*$___________ rubber is generally used for making 'O' rings used for v

1.	*$___________ rubber is generally used for making 'O' rings used for vacuum sealings.?
A.	Natural
B.	Neoprene
C.	Butadiene
D.	Nitrile
Answer» C. Butadiene