The correct answer is Sentence 6 "However, the truth is that the money spent on space exploration is critical to solving our problems on Earth"
Step-by-step explanation:
In essays, a thesis statement, also called a claim, is a sentence or statement that guides the essay and expresses a position of someone in regards to some topic, situation or issue. This type of statements go beyond reporting facts or telling the opinion of someone by formulating a claim that requires evidence to be supported or proved as valid, this implies thesis statements are debatable. Additionally, in essays, the thesis statement is presented at the end of the introduction paragraph and after the context of the topic has been provided in this way the reader can know the discussion that the author will develop during the text. Considering the previous ideas, the sentence that is the thesis statement in the paragraph presented is Sentence 6 "However, the truth is that the money spent on space exploration is critical to solving our problems on Earth" because this sentence is the only one from the options provided that express a specific position and not an opinion or fact, also, this statement is debatable which means it is suitable for an essay as the author will need to provide evidence to prove it and it appears after the introduction of the general topic which is common for presenting thesis statements in essays.