A botanist is trying to isolate all of the auxin produced in a bean plant by extracting it from seedlings in a range of developmental stages. Which of the following features of plant hormones must the scientist take into consideration while planning the extraction protocol?
A. They have a single specific role.
B. They affect mainly the cells that produce them.
C. They are species-specific.
D. They are produced in many different parts of the plant.
E. They elicit rapid responses.