The correct answer is: A. Zero internal resistance.
An ideal voltage source is a theoretical device that maintains a constant voltage across its terminals regardless of the current drawn from it. This means that it has zero internal resistance.
A real voltage source, on the other hand, has some finite internal resistance. This resistance causes the voltage across the terminals to drop as the current drawn increases.
The load-dependent voltage and load-dependent current options are incorrect because an ideal voltage source does not have a load-dependent voltage or current.
The answer to the question is A. Zero internal resistance.