A group of students conducted an experiment to identify the growth substance responsible for flowering and leaf development in plants. They did the investigation on 10 flowering plants which were divided into two plant groups, 5 plants on Group A and the other 5 on Group B. The plants were placed in the same environment and the conditions were kept constant for all plants. However, Group A was sprayed with gibberellins whereas Group B was left with the the natural amount of gibberellins. After a week, Group A had more flowers and leaves than Group B. After having made these observations, the students then concluded that gibberellins are responsible for flowering and leaf development in plants. What kind of reasoning is this?