A.immediately after receiving the first packet on the shared tree for a given (S,G)
B.after receiving over 1 kb/s traffic onthe shared tree for a given (S,G)
C.10 seconds after receiving the first packet on the shared tree for a given (S,G)
D.30 seconds after receiving the first packet on the shared tree for a given (S,G)
E.after receiving over 10 kb/s traffic onthe shared tree for a given (S,G)