Let's suppose we have P plans, and our goal is to study two different types of traits within that P plan. So we want to study the height of that pea plan as well as the seed color of that pea plan. So our two traits are height and seed color. Now, we have two possibilities for height. We have tall height and we have short height. And likewise, we have two possibilities for the seat color, we have yellow and we have green seat colors.