D. He controlled variables by studying one or two traits at a time
Well, the domain humans belong to (when I did a little research) is that they are actually a Eukaryote. Therefore, I'd say C, Eukarya. I hope this helps! ~Mia
Every plant organ is adapted to its function. For example, leaves that are big and flat absorb plenty of sunlight for photosynthesis. Long roots keep a tree stable and take water from deep in the soil. Some plants have unusual adaptations.
