Explanation: Traits usually die off when they are unneeded by the organism, or if the trait causes harm to the organism's survival. Through natural selection, over time, the organisms with the best combination of traits for its survival will become the dominating species, and those with weaker traits may not survive long enough to pass off their traits to future offspring.
I would love to answer this question for you, sadly you have not provided us with the diagram. So I am not able to see which type of plant experienced a drought.
