There's no way to tell for sure which plant will grow faster, because we don't know if a plant gets any benefit from red light.
But we do know for sure that it won't be the one we shine green light on. We know that green light is no use to green plants at all ... that's why when green light falls on them, they don't even bother absorbing it. They just let it bounce off, and that's why they look green to us.
The time it takes for 14C to radioactively decay is described by its half-life. C has a half-life of 5,730 years. In other words, after 5,730 years, only half of the original amount of 14C remains in a sample of organic material. After an additional 5,730 years–or 11,460 years total–only a quarter of the 14C remains.