What is the function of the "S bit" in the MPLS header?
A.
It is a service bit which when set indicates this label is active.
B.
It is a bottom of stack bit which when set indicated that this is not the last label in the stack.
C.
It is a bottom of stack bit which when set it indicates that this is the last label in the stack.
D.
It is a service bit which when set indicates this label is not active.