Which of the following indicates that an antenna cable should be replaced?

The indication that an antenna cable needs to be replaced is highlighted by the presence of dents or kinks in the cable. Such physical deformities compromise the cable's integrity and performance. A dent or kink can lead to damage within the cable, which may interfere with the transmission and reception of signals. This can result in degraded performance of the avionics systems that rely on accurate data from antennas.

In contrast, the other options do not necessarily indicate that a cable needs replacement. A different color does not inherently affect the functionality or performance of the antenna cable; it may simply reflect a change in manufacturing batches or materials. A longer length may not be a problem in itself unless it introduces issues with signal loss or excess slack. Additionally, the grounding of an antenna cable is critical for preventing interference and improving performance, but a cable can still function without an adequate ground point, although its effectiveness may be diminished, thus making grounding important but not an exclusive indicator for replacement.