When installing a security system， which of the following connectors would be used to connect the security system to the telephone service demarcation？（）

A.Determines the ambient light at night with a photocell.
B.Calculates sunset and sunrise times based on geographical area.
C.Determines the start and end of each of the seasons.
D.Synchronizes the local time displayed with the official world time.

A.fire proof
B.fiberglass coated
C.plenum rated
D.teflon coated

A.Directly to the left and right and slightly in front of the listener
B.Directly to the left and right and slightly behind the listener
C.Above and behind the listener
D.Directly behind the listener