Answer:
Answer is A. allow them to control all the variables involved.
Explanation:
Modelling in ecology means the use of constructed mathematical models for understanding of ecological processes and to predict or know how real it is for ecosystem to change.
Ecological modelling is useful in defining problems more precisely and clarity of concepts.
Image result for how does vascular system serve the needs of plant cells
Xylem and phloem make up the big transportation system of vascular plants. As you get bigger, it is more difficult to transport nutrients, water, and sugars around your body. ... The bottom is a system of roots. Each needs the other to survive.