Electrical circuits are protected against overheating by means of a/an （）.

A.keeping the terminals clean
B.coating cable connections with petroleum jelly
C.maintaining a trickle charge
D.All of the above

A.Any time it is deemed necessary
B.Only with the masters permission
C.After a 10 minute delay to the input command
D.Only after the throttle has been placed in stop

A.has high resistance at low temperatures
B.has a highly polished surface
C.is able to pass current with little opposition
D.holds insulation together well