How does a controlled experiment compare results

What causes darkening of the skin as melanin production increases

An ecologist studied the same species of deer during the summer and the winter. she noticed that during the summer, when there was plenty of food, the deer were energetic and playful. however, during winter when food was scarce, the deer moved more slowly and did not run unless they needed to escape a predator. which scientific fact is best supported by her observations?

The cretaceous period spanned the time interval between and 65 million years ago. 250 million 144 million 75 million 200 million