As a senior in high school, it is important for you to be able to take a generic topic and turn it into your own thesis statement. Therefore, rather than provide you with a thesis statement, I'll give you some steps to take so that you can write your own. These steps can be used with almost any essay topic or novel. This way, in the future, you'll be equipped to tackle writing assignments and essay prompts on your own.
The first step in a prompt that is this general is to turn the topic into an open-ended topic question. Here are a few examples to help get you started:
In No Country for Old Men, what major choices does the main character(s) make and how does it affect him/them?
What are the (negative or positive) consequences of a major decision (choice) in the novel?
The next step is to brainstorm general answers to your topic question(s). By brainstorming answers to one of the above questions, your ideas might lead you to a better and more specific topic question. An example might be:
What are the consequences of [certain choice(s)] and how do they affect the character/outcome of the story/reader/etc?
Notice how each of these sample questions could lead you to a variety of answers that must be supported by the text. As you brainstorm different ideas, be as specific as possible and include actual examples of what you are trying to say.
Once you've made a long list of ideas and examples (which will be used as evidence) narrow down your topic into one main focus. This means, choose a path or a direction for your essay. Maybe you want to focus on one choice and its many consequences. Maybe you want to focus on a common consequence of several bad/good choices.
If you can create a really well written topic question, your thesis statement simply answers that question in a complete sentence. The thesis for your essay should be completely up to you. It will not only reflect what you know and understand, but when you are in control, you have the best chance of writing a strong essay.
If making a decision for the direction of your essay is difficult, I advise you to look at all of your brainstormed ideas. Which one(s) will best lead you to three subtopics? Keep in mind that a five paragraph essay will need to be broken into 3 body paragraphs. Be sure your overall focus is divisible by three subtopics and use these subtopics as the general answer to your topic question, and your thesis statement is complete.