Final answer:
The statement that best supports Wilson's recognition of the need for international cooperation for peace is option B, which encapsulates Wilson's vision of collective security within the League of Nations.
Step-by-step explanation:
The statement from the text that supports the idea that President Wilson recognizes the importance of cooperation among countries in maintaining peace is B: "Only a peace the very principle of which is equally and a common participation in a common benefit." This statement reflects the core tenet of the League of Nations founded by Wilson, which was based on collective security. Each member nation, regardless of size or power, was to defend all others against military threats, thereby ensuring equal power and emphasizing cooperation for mutual benefit.
Controlling variables like the amount of water, the type of soil, etc., are crucial for drawing accurate conclusions about the impact of the experimental treatment alone. The lack of a proper controlled experiment could lead to incorrect interpretations of the data.