16. Which of the following is an observation? a. Trees need sunlight, water and the nutrients from the soil to grow well. b. Trees are very important in the ecosystem. c. Plants need carbon dioxide. d. The leaves of the plants are green. 17. Arnold wanted to be better understood on his observations. He presented this in his report. What did he use in communicating his ideas? a.graph b. table c. drawing or illustration d. concept map​