Answer:
D) Grounding
Explanation:
The potential difference between cloud and ground leads to ionization of the atmosphere and resulting conduction through the air often to ground (although it can be between clouds at different potentials. I would say grounding, like the spark when you touch a hot battery terminal to ground on a car.
The complementary base pair is:
TTC, CTG, AGT, CTA.
It depends whether or not the object in moving relative or not to the reference point, for instance imagine a void where there were no dimensions, but there was an object. You can’t tell if the object is moving or not without a reference point.