Which statement is TRUE concerning insulating flanges?

A
They should be inspected and tested periodically to ensure that the insulation is clean and in good condition.
B
Switching off a cathodic protection system may be substituted for using an insulating flange
C
The measured resistance value after installation should be less than 1000 ohms.
D
A bonding cable is more effective than an insulating flange or a single length of non-conductive length of cargo hose.
E