What is the appropriate order of the stages of investigating…

What is the appropriate order of the stages of investigating whether maple trees drop their leaves in the autumn because of colder days? 1- Maple trees are grown in 2 greenhouses where the only variable is temperature (15 C vs. 10CC). 2- The observation is that maple trees drop their leaves in autumn. 3- There is no statistical difference in the number of leaves dropped at 10 C as compared to 15CC. 4- The hypothesis is rejected. 5- The hypothesis is that maple trees drop their leaves because of colder temperatures.