Scientists have been experimenting with gene therapy, which often involves the use of bacteria or viruses to deliver new or modified genes to cells. these scientists believe gene therapy can be used to treat inherited diseases, but it is not yet in wide use even though many people have studied it. which statement best describes gene therapy?

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?