Answer:
a. your observations about the topic.
Explanation:
A thesis statement is a short statement giving your ideas or take on the claim that you are making in the thesis. It is a summarized version stating the main idea of the paper and your views on it.
A thesis statement of any literary or academic paper contains just a few sentences that contain the main ideas dealt or made in the whole thesis. This statement/ section is a form of asserting one's position in the claim made, making one's position clear to the readers and what the whole paper deals with. Thus, the one element that will be a part of a thesis statement must be one's observations about the thesis topic.
Thus, the correct answer is option a.
