Answer: 2 in 4
Explanation: if the parents are both RB, one would end up red, one would end up blue, and 2 would be heterozygous and end up presenting the incompletely dominant color of purple.
The goal was to see if Earth's ecosystems could be successfully manufactured and maintained elsewhere in the galaxy, should we need to bail on this planet.
It was named Biosphere 2 because it was meant to be the second fully self-sufficient biosphere, after the Earth itself