Ability to grow in shade may help pines found in the dry forests of Arizona resist drought. How well do these pines grow in shade? Investigators planted pine seedlings in a greenhouse in either full light, light reduced to 25% of normal by shade cloth, or light reduced to 5% of normal. At the end of the study, they dried the young trees and weighed them. (a) What type of study is this? Observational study: prospective Observational study: retrospective Observational study: cross-sectional Experiment: matched pairs design Experiment: randomized block design Experiment: completely randomized design (b) Match each of the following terms to the appropriate description. Pine seedlings a. Explanatory variable Amount of light b. Individuals Full light, light reduced to 25% of normal, light reduced to 5% of normal c. Response variable Weight d. Treatments