The correct answer is A: Both the United States and the Soviet Union possessed many destructive weapons. The purpose of the thesis statement is to state the main idea of the essay, i.e. it names the specific topic and gives the reader a general idea of the content of the essay. According to the student’s thesis above, the essay will be about the reasons why the United States and the Soviet Union were the two most powerful countries in the world by 1950; consequently, all the claims to support this thesis should be about these reasons. Though answers B and C refer to reasons why each of these countries were powerful, using one of these claims would be incorrect because they only make reference to one of these countries, making the essay unbalanced. Answer D is incorrect because it contrasts their ideologies, but it is not a reason why the USA and the USSR were the most powerful countries in the world. Answer A is correct because it presents a claim that supports the idea presented in the thesis as it makes reference to a reason why both countries were powerful in 1950; they both possessed destructive weapons, such as the A-bomb and H-bomb. In fact, during the 1950s, there was a nuclear arms race between these two superpowers, which competed for supremacy in nuclear warfare.