Cathodic Protection of a Metal Pipe Against Corrosion Usually Entails

Cathodic protection of a metal pipe against corrosion usually entails

A) attaching an active metal to make the pipe the anode in an electrochemical cell.
B) coating the pipe with a fluoropolymer to act as a source of fluoride ion (since the latter is so hard to oxidize)
C) coating the pipe with another metal whose standard reduction potential is less negative than that of the pipe.
D) attaching a dry cell to reduce any metal ions which might be formed.
E) attaching an active metal to make the pipe the cathode in an electrochemical cell.