The correct answer is C: Bond them together with heavy wire or conductive strap. All external ground rods or earth connections should be bonded together with heavy wire or conductive strap. This creates a single, low-resistance ground system. If ground rods aren't bonded, they can be at different potentials, creating dangerous voltage differences and reducing lightning protection effectiveness. For amateur radio operators, proper ground bonding is essential for safety and effective lightning protection. Understanding this helps create a proper ground system.