QUESTION 4 The thickness of the annual rings in stems indicates the type of environmental condition that was occurre during the time of the tree's development. A thin ring usually indicates a rough period of development s as lack of water, forest fires or insect infestation. A thick ring means a prosperous period of developmer An investigation done in two forests (A and B) provided the following results: Age of trees (years) Average thickness of annual rings in Forest A (millimetres) 20 24 30 34 41 Average thickness of annual rings in Forest B (millimetres) 24 28 35 38 10 20 30 40 50 45 60 46 51 4.1 Identify the following in the investigation. (a) Dependent variable. (b) Independent variable. anud finge 42 What was the average thickness of the annual rings for 40-year-old trees in Forest A? 3 What was the average thickness of annual rings for all the trees found in Forest B? Show ALL your calculations graph answers ​