1.b
2.a
1. Thesis Statement: On May 5, 1862, the Mexican government announced to the world that foreign intervention in its affairs would no longer be tolerated. Although the Mexican-American War (1846 -- 48) might have left the country weary and bankrupt, that did not mean foreign intrusion would be met with no resistance. The fifth of May, or Cinco de Mayo, proved that once and for all.
Note: I would also accept as correct just the first sentence beginning with On and ending with tolerated. It doesn’t sum up the reading as effectively, but it can act as a summary statement, which is the essential requirement of a thesis statement.
2. Thesis Statement: Numerous psychology textbooks have dutifully passed on to students the notion that the “Hawthorne effect” was a scientific finding grounded in solid research. Yet, in reality, the Hawthorne effect was based on very shaky evidence.