Answer:
The thesis for this particular excerpt would be option A - In the 1800s, the United States was still a very young nation, trying to solidify its identity. A thesis is the statement that an author will put forward to be maintained, and from the available information from the question, it seems likely that this particular sentence will be the correct answer.
Step-by-step explanation:
the thesis is In the 1800s, the United States was still a very young nation, trying to solidify its identity. hope it helped