Hello again!
If plants are purebred, then they are homozygous. This means that they have the exact same genes in one pair: for example, AA. If they are both purebred, then the dominant gene will win out every time. The answer for this question, then, would be D. Here is a diagram to help you!
Potassium is just below the sodium in periodic table in s group !
so the valence electron of sodium and potassium is same and that is 1 !
A Punnet Square is what you're looking for :)