Questions like this should not be on a test. What is "protected from physical damage" is not well defined in the code and is usually the inspectors call. If this cable was a 7' 1" would it be protected? How about 8', or 10'? Is there any guarding on the fence? Questions like this need to explicitly tell you if the conductors have been deemed to be subject to physical damage or severe physical damage or not subject to damage. There are only a few places in the code where you're explicitly told that a conductor of size X is OK even if subject to (severe) physical damage.
